DURHAM, Justice:
The defendant and appellant, Kathy Tanner, appeals from her conviction for manslaughter in the death of her three-year-old daughter. The defendant was tried before the court and sentenced to an indeterminate term of not less than one or more than fifteen years in prison. The defendant here argues that there was insufficient evidence to -support the verdict, that some evidence was erroneously admitted, and that some evidence was erroneously excluded.
The key evidence in this case is the mute testimony of the body of three-year-old Tawnya Tanner. There is no question that she died on March 21, 1980, of “subdural hematoma associated with multiple contusions of the body,” as stated in the autopsy report. That report, the contents of which were stipulated to by the defendant, enumerated the many contusions scattered over the child’s body literally from head to foot. The contusions are clearly visible in the photographs admitted in evidence, as are the bulges of the scalp where the severely bruised brain protruded through the craniotomy sites. At trial the court permitted the prosecution’s medical experts to testify regarding the condition of the child’s body, the nature of the injuries and the cause of death. This testimony included the witnesses’ observations regarding the “battered child syndrome.” The defendant claims error in the admission of this battered child syndrome testimony and the admission of instances of prior bad acts that she alleges were presented “to establish that Tawnya was a victim of the Battered Child Syndrome.”
The issue of the admissibility of “battered child syndrome” testimony has not previously been presented to this Court.1 The development of the medical-social concept of the battered child syndrome is traced in McCoid, “The Battered Child & Other Assaults Upon the Family: Part One” 50 Minn.L.Rev. 1 (1965). The author points out that the “development of the concept of the battered child syndrome has moved from an initial identification of physical phenomenon [sic] to concern with the causative factors outside of the body of the [542]*542child.” Id. at 19. Early publications concentrated on the identification of the pattern of injuries observed, but in the 1950s, articles began to address the origins of the trauma, including the role of the parents. Increasingly, as attention and research focused on the problem and statistics were assembled, the medical profession became aware of the abusive character of the injuries and the grave danger to the helpless child in the custody of an abusive caretaker. Id. at'4-8. McCoid summarizes:
From this review, it appears that by early 1965, there had come a recognition of a distinctive phenomenon called “the battered child syndrome” which, though it begins with a pattern of injuries to the child, is really descriptive of a pattern of conduct on the part of the parents or others who are to guard the welfare of the child. The medical description can perhaps best be summarized as multiple injuries in various stages of healing, primarily to the long bones and soft tissues and frequently coupled with poor hygiene and malnutrition, but peculiarly identified by the marked discrepancy between the clinical or physical findings and the historical data provided by the parents. Described in terms of the conduct of the parents or their characteristics, the studies seem to confirm that the abuser is likely to be an emotionally immature individual from almost any walk or stratum of society, a person who probably suffers from the pressures of marital difficulties or economic circumstances or other emotional pressures not directly related to the child himself, so that the child becomes merely a focus for generalized frustration or anger and an outlet for the poorly controlled aggressiveness of the parent.
Id. at 18-19.
Over the past fifteen years, cases discussing the use of battered child syndrome evidence have appeared with increasing frequency in the state reporters. The battered child syndrome has become a well-recognized medical diagnosis, which must be testified to, by an expert witness:
The diagnosis is dependent on inferences, not a matter of common knowledge, but within the area of expertise of physicians whose familiarity with numerous instances of injuries accidentally caused qualifies them to express with reasonable probability that a particular injury or group of injuries to a child is not accidental or is not consistent with the explanation offered therefor but is instead the result of physical abuse by a person of mature strength.
State v. Mulder, 29 Wash.App. 513, 629 P.2d 462, 463 (1981). In People v. Jackson, 18 Cal.App.3d 504, 95 Cal.Rptr. 919 (1971), the court pointed out that “[a]n expert medical witness may give his opinion as to the means used to inflict a particular injury, based on his deduction from the appearance of the injury itself.” Id. at 507, 95 Cal.Rptr. at 921. Such testimony is not accusatory, but only indicates the cause of death. Similarly, when an expert testifies as to the existence of the “battered child syndrome,” he expresses no opinion regarding a defendant’s culpability, but rather testifies that, as the witness in Jackson stated:
“[I]t would take thousands of children to have the severity and number and degree of injuries that this child had over the span of time that we had” by accidental means. In other words, the “battered child syndrome” simply indicates that a child found with the type of injuries outlined above has not suffered those injuries by accidental means. This conclusion is based upon an extensive study of the subject by medical science.
Id.2 In Bludsworth v. State, Nev., 646 P.2d 558 (1982), the defendants argued that [543]*543evidence of bruises and a bite mark on the body of the child was incompetent because there was no prior establishment that either defendant was responsible for the injuries. The court affirmed the admission of the evidence, stating:
Admissibility of the bite mark and other bruise evidence does not depend on connecting either defendant to the infliction of the injury. It is independent, relevant circumstantial evidence tending to show that the child was intentionally, rather than accidentally, injured on the day in question.
Id. at 559. In People v. Dejesus, 71 Ill. App.3d 235, 27 Ill.Dec. 448, 389 N.E.2d 260 (1979), the defendant claimed error in the use of battered child syndrome evidence, arguing that it suggested to the jury that the defendant was guilty of prior offenses. The court held that the expert’s diagnosis and explanation of medical terms of art do not indicate wrongdoing on the part of a particular defendant, but merely describe the nature of the injuries. See also State v. Wilkerson, 295 N.C. 559, 247 S.E.2d 905 (1978); State v. Goblirsch, 309 Minn. 401, 246 N.W.2d 12 (1976).
The defendants in these cases frequently argue that evidence of injuries other than that which is the immediate cause of death, i.e., any evidence of the battered child syndrome, is incompetent or is more prejudicial than probative. Again, we emphasize that evidence regarding the child’s physical condition does not directly indicate the culpability of any particular defendant. In Ashford v. State, Okl.Crim., 603 P.2d 1162 (1979), an 8-month-old baby was found to have injuries from five days to two weeks old and partially healed fractures from four to eight weeks old, in addition to a fatal subdural hemorrhage. The court held that “[i]n a case of this nature, the past injuries are admissible to counter any claim that the latest injury happened through accident or simple negligence. The pattern of abuse is relevant to show the intent of the act.” Id. at 1164 (emphasis added). In other words, the pattern of abuse is relevant to show that someone injured the child intentionally, rather than accidentally.
Battered child syndrome evidence is most frequently cited as admissible to show absence of accident. It is relevant to claims of accidents by the child, e.g., “She was clumsy and fell a lot,” as well as accidents by the adult, “I tripped while I was carrying him.” Expert testimony as to types of injuries, their size, location and severity, together with evidence of their varying age and progress in healing, allows the lifeless or preverbal victim to testify in the only way possible. We are satisfied that the concept of the battered child syndrome is grounded in scientific research and is widely accepted in the medical community. Our research shows that all courts which have addressed the question have affirmed the admission of expert medical testimony regarding the presence of the battered child syndrome. We therefore conclude that in appropriate factual circumstances, testimony regarding the battered child syndrome is admissible when given by a properly qualified expert witness.3 We caution trial courts to weigh [544]*544carefully the probative value against the potential for undue prejudice that may be created by the use of the term “battered child syndrome.” The term should not be applied broadly or as a generalization. The expert should be able to testify in detail regarding the nature of the child’s injuries and whether the explanation given for the injuries is reasonable. Any deficiencies in the testimony, however, go to its weight rather than to its admissibility. The weight and credibility to be given an expert’s testimony are matters to be decided by the factfinder. Defense counsel may of course challenge the testimony on cross-examination, but such challenge goes to the weight to be given the testimony, not to its admissibility. See State v. Clayton, Utah, 646 P.2d 723, 726 (1982).
In the instant case, the testimony of four medical experts was presented by the State. The doctor on duty in the emergency room described Tawnya’s condition as “moribund,” in other words, a dying condition. He testified that the defendant told him that Tawnya fell, but that the explanation did not seem consistent with the severity of the child’s condition. A neurosurgeon was the next to examine Tawnya. He testified that he found no spontaneous respiration, that Tawnya had dilated pupils with hemorrhages in the right eye indicating intercranial pressure, and that he observed one acute “relative fresh” bruise just ahead of the right ear, several new and old bruises on the face and an old bruise on the inner thigh. He further testified that he performed a bilateral craniotomy to relieve the pressure on the brain and that he found a very large subdural hematoma or blood clot with bruised brain tissue. He stated that the severity of the swelling and the hematoma indicated that a significant amount of force had been applied. Tawnya died the next morning, never having regained consciousness.
As already mentioned, the autopsy report stating that Tawnya died of “subdural he-matoma associated with multiple contusions of the body” was stipulated to at trial. The medical examiner’s expert opinion was that the multiple bruises on Tawn-ya’s chin were not consistent with a single fall. The State’s fourth expert, Dr. Palmer, based his opinion on his review of the police records, the autopsy report, the neurosurgeon’s report, and his extensive experience as a pediatrician specializing in the study of child abuse. Dr. Palmer testified regarding the phenomena that alert a physician to the possibility of the battered child syndrome, such as: too many bruises and bruises in atypical locations considering the child’s age; fractures, such as spiral fractures, of a type and severity not otherwise explained; severe head injuries not otherwise explained; and in general, a history of the trauma given by a caretaker that is inconsistent with the child’s injuries. The doctor also testified that abusive disciplinary methods are frequently part of the battered child syndrome, that the parents of such children are typically very young or inexperienced and that they are likely to have a history of prior abusive conduct. Dr. Palmer went on to identify in Tawnya the characteristics of the battered child, emphasizing in particular the inadequate explanation given by the defendant for Tawnya’s injuries. Counsel for the defendant took full advantage of the opportunity to challenge Dr. Palmer’s opinions and the bases for his conclusions.
All four of the State’s experts were properly qualified and testified within their areas of expertise. The term “battered child [545]*545syndrome” was not used broadly, but was defined and applied to Tawnya with particularity. We therefore find that the trial court did not err by admitting testimony regarding the battered child syndrome.
The defendant also alleges error in the admission of testimony regarding specific instances of prior bad acts. She refers to Rule 47 of the Utah Rules of Evidence, which prohibits the use of evidence of specific conduct which tends to prove that a trait of the defendant’s character is bad. She also cites Rule 55 of the Utah Rules of Evidence, which makes inadmissible evidence that the defendant committed a crime or civil wrong on a particular occasion for the purpose of inferring that the defendant committed a crime or wrong on another occasion. She alleges that evidence of prior bad acts was offered to establish the existence of the battered child syndrome. In this she is mistaken. The testimony regarding the battered child syndrome was based on the experts’ observations of Tawnya’s damaged body and was independent of evidence of the defendant’s conduct.
The defendant also relies on Rules 47 and 55 of the Utah Rules of Evidence to contest the admission in evidence of specific instances of her prior conduct. This same allegation of error is raised in nearly all of the cases of a similar nature that we have reviewed. For example, in State v. Tucker, 181 Conn. 406, 435 A.2d 986 (1980), witnesses testified that they had seen the defendant abuse the 16-month-old victim, such as dropping the child from his bicycle, shaking him violently, causing him to fall out of his stroller and to hit his head, and slapping and hitting him. The defendant challenged the admission of the testimony as lacking probative value with regard to the intent to commit murder, and further argued that, even if probative, the evidence should have been excluded as prejudicial. The court held that the evidence was relevant to establish “a pattern of behavior and an attitude toward the child that is indicative of the defendant’s state of mind.” Id. at 415, 435 A.2d at 991. The court also found the evidence admissible to show that the child’s death was the result of an intentional act rather than an accidental act. In People v. Henson, 33 N.Y.2d 63, 304 N.E.2d 358, 349 N.Y.S.2d 657 (1973), the court held that evidence of the defendant parents’ prior abusive acts was admissible to show absence of accident or mistake. The court stated that evidence of the battered child syndrome, together with other evidence such as the injuries having been caused while the child was in the parents’ sole custody, permits the jury to infer that the child’s injuries were not accidental and that the injuries were caused by the parents.
In the case before us, the defendant objects to the testimony regarding her treatment of Tawnya, alleging that its admission violated Rule 47 by attempting to prove a bad character trait with specific instances of conduct other than a conviction of a crime. She argues further that such evidence is not admissible as one of the exceptions under Rule 55, such as admissibility to show absence of mistake or accident, motive, opportunity, intent, plan, etc., because she did not raise the defense of accident or mistake. We agree with the courts in the Tucker and Henson decisions, supra, that such instances do tend to show that the crime charged was the result of intentional rather than accidental acts, but we find it unnecessary to base the admissibility of this evidence on whether or not the defendant has raised the defense of accident or mistake, or indeed, on any of the exceptions listed in Rule 55. In State v. Forsyth, Utah, 641 P.2d 1172 (1982), this Court pointed out that the word “including,” which precedes the list of exceptions in Rule 55, “indicates that the list is illustrative, not exhaustive.”
Thus, Rule 55 provides that ... “other crime evidence” is admissible when relevant to prove any material fact, including those listed, but not including criminal disposition_
Id. at 1175. The policy underlying Rule 55 is to assure that the criminal defendant is convicted of the crime charged and is to [546]*546protect him from conviction for being a person of criminal character. This policy is praised and promulgated everywhere, but the various formulations of the rule arising from the policy support a confusing body of case law. Historical research suggests that the original English rule, adopted in the United States, was very narrow in scope, excluding only evidence of acts that were relevant merely to disposition. See Stone, J., “The Rule of Exclusion of Similar Fact Evidence: America,” 51 Harv.L.Rev. 988, 993 (1938). However, by the mid-nineteenth century, the admission of any evidence of other crimes or civil wrongs began to be described as anomalous, i.e., as an exception to a general rule of evidence excluding all such evidence. The original or inclusionary version directs the inquiry to relevance: if the evidence sought to be admitted is relevant and relevant to a matter other than the defendant’s disposition, the evidence is admissible. The later exclusionary rule directs inquiry to the exceptions to the rule: if the evidence does not fit within a recognized exception, it is excluded. The exclusionary version of the rule is subject to abusive use in that it may prompt exclusion of clearly relevant evidence because of the difficulty in placing the evidence within an acceptable category, or it may be applied to admit evidence of questionable relevance merely because the evidence falls within a recognized exception. The application of the exclusionary version appears temptingly simple, but its mechanical use may in some circumstances deprive the defendant of the very protection that the underlying policy would provide, while in other circumstances it may impose an unnecessary and sometimes insurmountable burden on the State.4 Many courts have observed that the more crimes or wrongs committed by a defendant, the more difficulty the prosecution may have in obtaining admissible evidence. See, e.g., State v. Nemier, 106 Utah 307, 148 P.2d 327 (1944).
Although this Court has at times cited both formulations of the rule, since State v. Scott, 111 Utah 9, 175 P.2d 1016 (1947), the Court has applied the inclusionary version. See Boyce, R., “Evidence of Other Crimes or Wrongdoing,” 51 Utah B.J. 31 (1977). Rule 55 of the Utah Rules of Evidence, adopted in 1971, appears at first glance to be a recitation of the exclusionary version, with its list of exceptions. However, as we pointed out in Forsyth, supra, this effect is produced by the syntax. The substance of the rule is inclusionary: evidence of other crimes or civil wrongs that is competent and relevant to prove some material fact, other than to show merely the general disposition of the defendant, is admissible. The determination of relevancy is within the discretion of the trial judge.
In cases of child abuse, such as the one before us, evidence of specific instances of the defendant’s treatment of the child is relevant to establish not merely a general disposition for violence or ill-will towards all children, but to establish a specific pattern of behavior by the defendant toward one particular child, the victim. We distinguish this evidence of the defendant’s conduct, relevant to establishing a pattern of behavior by the defendant, from evidence of the battered child syndrome given by experts that is relevant to establishing the nature of the injuries to the child and that is nonaccusatory and independently admissible, as discussed, supra. The two categories of evidence should, of course, be corroborative in order to support a conviction. This pattern of behavior by the defendant is relevant to establishing absence of accident or mistake (as held by numerous courts),5 opportunity, knowledge or the [547]*547identity of the defendant as the person responsible for the crime charged.
We note that the courts of Nevada and Arizona have recognized that prior acts of sexual misconduct may be relevant to establish a “specific emotional propensity for sexual aberration.” State v. McDaniel, 80 Ariz. 381, 388, 298 P.2d 798, 802 (1956). The evidence is limited to “proof of similar acts near in time to the offense charged.” State v. McFarlin, 110 Ariz. 225, 228, 517 P.2d 87, 90 (1973) (emphasis added). See also McMichael v. State, 94 Nev. 184, 577 P.2d 398 (1978). Analogous reasoning is appropriate in a case such as this one where the presence of the battered child syndrome has been identified in the child. As previously noted (see McCoid, supra), the child abuser may be from any walk or stratum of society and not overtly remarkable in other ways. Medical research indicates that the child becomes the focus for the abuser’s frustration or anger. Evidence of other violence or anger as, for example, abuse of other adults or inanimate objects, is too general to be relevant to the specific emotional propensity to abuse a child. While recognizing the relevance of specific instances of prior abuse, however, we refrain from specifying “specific emotional propensity” as a special category or exception to be added to the list contained in Rule 55. Such exceptions are subject to arbitrary and rigid use, as discussed above. The same danger exists in attempting to avoid Rule 55 by categorizing specific instances of prior abuse as habit or custom, under Rule 50. Although evidence of habit is far more specific than evidence of character and therefore less likely to be unduly prejudicial, complete avoidance of Rule 55 may lead to avoidance of the central consideration, i.e., relevance. See McCormick, supra, note 3, § 195. There is no substitute for a case-by-case inquiry into relevance.
Even when admissible as relevant, evidence of other crimes or civil wrongs may be excluded under Rule 45 if the trial judge finds that the probative value is substantially outweighed by the risk that its admission will consume unnecessary time, cause undue prejudice, or unfairly surprise a party. In order to preserve the policy underlying Rule 55 (conviction for commission of the crime charged and not for a criminal disposition), the judge must weigh not only the probative value of the evidence but also the need for the evidence and the necessity for a “full inquiry into the facts relating to the issues” against the potential for undue prejudice to the defendant. State v. Lopez, 22 Utah 2d 257, 262, 451 P.2d 772, 775 (1969). Where there is child abuse, there will invariably be secrecy. The great disparity of power and control between the abuser and the child assures that there will be little, if any, direct evidence. Even in cases where the victim survives, the child’s age and vulnerability make it unlikely that he or she could be expected to testify competently. In these cases, it is probable that evidence of prior abusive conduct by a caretaker may be the only available link between the specific nature of the child’s injuries and the caretaker who has offered either no explanation or an inadequate explanation for those injuries. However, we emphasize that the “reception of such evidence is justified by necessity and, if other evidence has substantially established the element of the crime involved (motive, intent, identity, absence of mistake, etc.), the probative value of showing another offense is diminished, and the trial court should rule it inadmissible even though relevant.” Tucker v. State, 82 Nev. 127, 412 P.2d 970, 971 (1966).
In the instant case, the defendant told the doctors who treated Tawnya that the three-year-old had fallen off a slide at the park. She called her cousin while Tawnya was in surgery and related the same story, which she also told to two police officers. The defendant claimed that Tawnya was unconscious when she arrived home from work and that Leland Foote, with whom the defendant was living, told her that Tawnya had fallen from a slide earlier that day when Tawnya and her five-year-old brother, Brian, played there. Indeed, Foote originally told police officers [548]*548that when the two children returned from the park, Tawnya had a minor nosebleed and said that she had fallen. He claimed that she ate her lunch normally and watched television and that he later found her unconscious on the floor. Foote subsequently pled guilty to manslaughter and testified against the defendant,6 relating that she disciplined Tawnya harshly, especially when Tawnya wet herself. He stated that on March 20, he and the defendant’s two small children walked to the defendant’s place of work to meet her and walk home with her, that Tawnya was lively and well,7 that after returning to their apartment, he went into the bathroom where he heard two loud thumps as if something heavy had been thrown against the wall in the next room and that when he left the bathroom, he saw the defendant watching TV and he saw Tawnya lying unconscious on the floor. Foote related specific instances of the defendant’s treatment of Tawnya, such as throwing her against a wall or the floor, kicking her, making her sit in a tub of cold water until the child could not stand, whipping her with a belt and rubbing the child’s face in her messy pants. Additional witnesses— Foote’s relatives, the defendant’s relatives and the defendant’s co-workers — corroborated this testimony by relating instances in which they personally saw the defendant abuse Tawnya or heard the defendant talk about disciplining Tawnya in ways they considered harsh. All of the incidents were personally observed by the witnesses, who were extensively cross-examined. The testimony was relevant not only to the absence of accident or mistake, as we noted above, but also to the defendant’s pattern of behavior toward the victim. Where the presence of the battered child syndrome is shown in the child and the defendant is the child’s caretaker, logic and the interests of justice demand as complete a story as possible concerning the crime and the surrounding circumstances. Medical testimony indicated that Tawnya’s fatal injury was part of a pattern of abusive injuries. Evidence of the defendant’s conduct during substantially all of Tawnya’s life establishes an explanation for the many nonfatal injuries found on Tawnya’s body. Professor Boyce comments that “in many instances evidence offered to complete the story of the crime also will establish identity, motive, scheme or plan or otherwise be admissible as bearing on a material fact in issue.” Boyce, supra at 53. Such is the case here. This evidence, together with the defendant’s lack of reasonable explanation for the injuries, is relevant to establish the identity of the one responsible for the fatal injury.
The defendant also objected to the admission of expert testimony regarding Tawn-ya’s physical condition as an infant. Dr. Palmer’s testimony was based on a report made by a physician who treated Tawnya at the Oregon Medical Center when Tawn-ya was three months old. Tawnya was admitted because of “failure to thrive,” a [549]*549condition that may be caused by a variety of physiological problems or by neglect or abuse. After her admission, a routine x-ray revealed that Tawnya had sustained fractures of the right clavical, the right eleventh rib, the right tibia, and that she had an abnormality of the left humerus. He observed that two of the fractures were spiral fractures and stated that a self-inflicted spiral or tortion fracture is inconsistent with the degree of mobility possible for a three-month-old infant. He also noted that the parents’ explanation of a fall from a couch was not sufficient to account for the injuries. Separate and apart from any evidence pertaining to the defendant’s conduct, he testified that these physical symptoms were all indicators that would alert a physician to the possibility of the battered child syndrome. Although Dr. Palmer’s testimony dealt only with Tawn-ya’s physical condition and contained no accusatory statements regarding the defendant, this evidence is not relevant to Tawnya’s condition at the time of her death, but rather is relevant to establishing a pattern of conduct by the defendant. The defendant points out that, although Tawnya was temporarily removed from her home as a result of this medical report, neither she nor Tawnya’s father was ever prosecuted or convicted for any abuse of Tawnya. The defendant therefore argues that the evidence was admitted in violation of Rule 47 of the Utah Rules of Evidence, claiming that evidence of her prior bad acts (including the medical reports from Oregon) was “an attempt to show a bad, violent, and uncaring character” and was an inquiry into matters beyond the scope of the trial. We disagree. Where expert testimony has established the presence of the battered child syndrome in the victim, the pattern of conduct exhibited by the defendant-caretaker toward the child-victim is within the scope of the issues before the court. Specific instances of the defendant’s prior acts were not admissible to show a generalized bad character, but to show the defendant’s pattern of conduct toward Tawnya, specifically. The medical records are admissible, not because they fit within one of the exceptions included in Rule 55, but because the medical records are highly relevant to complete the whole history of the defendant’s conduct toward Tawnya and because the records are reliable.
The physician is undoubtedly a skilled observer of physical phenomena and is well equipped to determine whether the physical manifestations which he discovers square with the medical history given by the parents or the description of the events leading up to the present condition of the child.
McCoid, supra at 46. Medical records of the child’s current or past condition that indicate either the presence or absence of abusive injuries must always be relevant to the issues at trial where, as here, expert testimony has established the presence of the battered child syndrome in the victim.
The question remains as to whether the trial court abused its discretion by admitting the evidence of the defendant’s pri- or conduct under the standards set forth in Rule 45 of the Utah Rules of Evidence. As we have discussed above, child abuse is most likely to occur in the privacy of the home under circumstances that make the existence of direct evidence rare. In this case, the victim could not testify, and there were no competent witnesses to the crime. Under such circumstances, the admission of highly relevant evidence regarding the defendant’s conduct toward the victim was justified by necessity and by the very specific nature of the evidence. It is questionable whether a three-year-old medical record standing alone, which strongly implied bad acts, would have sufficient probative value to outweigh the substantial risk of undue prejudice to the defendant. However, in this case the medical report, together with testimony of abusive conduct of a contemporary and ongoing nature, is highly probative and outweighs the risk of undue prejudice. Therefore, we find no abuse of the trial court’s discretion.
The defendant also alleges error in the trial court’s exclusion of statements made by Brian Tanner, the defendant’s five-year-[550]*550old son. Brian was questioned by police officers the day after Tawnya was injured. It is clear that Brian’s statements were not spontaneous but were in response to questions that were often leading. There was no cross-examination. However, at the preliminary hearing, the court interviewed Brian to determine his competency, and he was examined at length by both the State and the defendant. The record shows that Brian was easily influenced by the questions asked, as counsel drew confusing and contradictory statements from him. The defendant herself then filed a motion in limine to exclude Brian’s testimony, claiming that he would not be able to testify with the reliability required by law, that he could not relate the events of the evening in question, and that he was highly susceptible to suggestion and given to fantasy.
At trial, the court questioned Brian prior to ruling on the defendant’s motion in limine. At that time, Brian would not respond, and the court ruled that he was incompetent to testify. Following that ruling, which in effect granted her motion, the defendant attempted to elicit the substance of Brian’s statements at the police interview from a police officer testifying for the prosecution. The trial court ruled that such testimony would be hearsay and that it was not admissible as an exception to the hearsay rule either as a contemporaneous statement or because Brian was unavailable.8 The defendant continued to object to Brian’s testimony given at the preliminary hearing that the prosecution attempted to introduce. The court excluded that testimony, also. The determination of competency of a minor is within the discretion of the trial court pursuant to the standards set out in State v. Smith, 16 Utah 2d 374, 401 P.2d 445 (1965). See, e.g., State v. Wilkerson, Utah, 612 P.2d 362 (1980). The court’s ruling will not be disturbed in the absence of a clear showing of abuse. The court, in person, attempted to interview Brian and made a firsthand assessment of his competency, which we will not second-guess. We find no abuse of the court’s discretion in ruling the witness incompetent to testify and in excluding his testimony.
Finally, the defendant argues that there was insufficient evidence to support the verdict. In reviewing a claim of insufficient evidence, this Court must view the evidence in the light most favorable to the verdict and will interfere only when the evidence is so lacking and insubstantial that a reasonable person could not possibly have reached a verdict beyond a reasonable doubt. See State v. McCardell, Utah, 652 P.2d 942 (1982), and cases cited. This standard of review is the same where the court, rather than a jury, acts as the finder of fact. See State in re K.K.H., Utah, 610 P.2d 849 (1980). The defendant claims that the circumstantial nature of the evidence, together with the evidence of a favorable polygraph test, is sufficient to show that a reasonable person could not possibly have reached a verdict beyond a reasonable doubt.
We have frequently stated that circumstantial evidence alone may be competent to establish the guilt of the accused. See, e.g., State v. Clayton, supra. The defendant emphasizes that in order to warrant conviction, circumstantial evidence must exclude every reasonable hypothesis other than the defendant’s guilt. See, e.g., State v. John, Utah, 586 P.2d 410 (1978). However, in order to meet this standard, the evidence need not exclude every hypothesis, “however unsubstantial or incredible, which a party to such a controversy may dream up.” Id. at 412. In Huerta v. State, Tex.App., 635 S.W.2d 847 (1982), the court stated that “[t]he rules of circumstantial evidence do not require that the circumstances should to a moral certainty actually exclude every hypothesis that the act may have been committed by another [551]*551person; but the hypothesis intended is a reasonable one consistent with the circumstances and facts proved.” Id. at 851 (quoting from Flores v. State, Tex.Cr.App., 551 S.W.2d 364, 367 (1977)) (emphasis in original). In Aldridge v. State, Miss., 398 So.2d 1308 (1981), the court addressed the same objection to circumstantial evidence:
To sustain a verdict based on circumstantial evidence, it is not necessary that such evidence exclude every possible doubt or theoretical supposition in no way related to the facts or circumstances of the case. It is enough that such evidence exclude every reasonable hypothesis of innocence.
Id. at 1311 (citation omitted). These statements, taken from cases involving similar fact situations, are in accord with our existing law and our view of the evidence in this case. The court was entitled not only to consider the evidence presented, but also to make reasonable inferences. See, e.g., State v. McCardell, supra. If circumstantial evidence and reasonable inferences were to be discounted, it is doubtful that convictions would ever be found in cases of this nature where the crime takes place in the home and where the youth of the victim, combined with the relationships of the family members, makes it difficult, if not impossible, to obtain direct evidence. See State v. Tucker, supra; State v. John, supra. In the instant case, competent evidence was presented that the child was the victim of a continuing pattern of abuse, that the defendant habitually abused the child, and that the defendant was present and in actual custody of the child when the injury occurred. The court was entitled to draw reasonable inferences and conclude that Tawnya died as a result of injuries inflicted by the defendant. There is no fact or circumstance in evidence that supports any other reasonable conclusion.
The defendant claims that the favorable results of the polygraph test that she took automatically raise a reasonable doubt as to her guilt.9 We do not agree. The court was not obligated to give more weight to that evidence than to other evidence presented. The weight and credibility given the evidence is decided by the finder of fact, in this case, the court. The court did not err in basing its conclusions on the other evidence before it. We do not hold that a favorable polygraph test raises a reasonable doubt as a matter of law.
The defendant’s conviction is affirmed.
HALL, C.J., and OAKS and HOWE, JJ., concur.