HARLINGTON WOOD, Jr., Circuit Judge.
Defendants Otha Dennis (“Dennis”) and James Brown, a/k/a Donald Ray Washington (‘Washington”), appeal from their convictions for attempting to possess cocaine with intent to distribute it. Washington and Dennis raise several issues. Both defendants challenge as invalid an anticipatory search warrant authorizing the search of Dennis’s apartment after a controlled delivery of an Express Mail package containing cocaine. Dennis also contends that the initial warrantless seizure of the Express Mail package violated his Fourth Amendment rights and that the government’s pre-trial discovery rule violations warrant a new trial. Washington, meanwhile, contends that the government presented insufficient evidence to support the guilty verdict against him. We affirm the defendants’ convictions on all grounds.
I. Background
On August 10,1995, a United States postal inspector determined that an Express Mail package mailed from Los Angeles and addressed to “Otha Dennies” at Dennis’s residence in Decatur, Illinois matched a narcotics package profile developed by the United States Postal Service. The inspector detained the package and had a trained drug detection dog sniff the package. After the dog signaled that narcotics were in the package, the inspector obtained a search warrant and opened the package. In addition to miscellaneous personal items, the inspector found approximately 16 ounces of eocaine. The inspector replaced a portion of the co-eaine, attached an electronic beeper to the inside of the package, resealed the package and obtained an anticipatory search warrant for the residence to which the package was addressed.
On the next day, the postal inspector, dressed as a mail carrier, delivered the package. When the inspector arrived at the Decatur address, he encountered Dennis and Washington sitting on the front porch. After the inspector announced that he had an Express Mail package for Dennis, Dennis signed for' the package and placed it on the corner of the porch. After surveying the area, Dennis picked up the package, and he and Washington went into the first floor apartment. After the defendants entered the apartment, the electronic beeper inside the package sounded, signaling that someone had opened the package.
The police entered the first floor apartment to execute the search warrant and apprehended Dennis in the bathroom while he was attempting to flush down the toilet a pair of socks that had been in the box. The police also found a tennis shoe next to the toilet. The cocaine had been hidden in socks stuffed in one of a pair of tennis shoes in the box. The police found a piece of paper containing the tracking number of the Express Mail package in Dennis’s wallet. In addition to these items, the police recovered baggies from the apartment. However, the police did not discover any other narcotics or indi-cia of narcotics trafficking, such as scales or cash, inside the residence. The police apprehended Washington as he attempted to flee from the apartment. When they stopped Washington, he identified himself as “James Brown” and produced a false California I.D. listing his residence as the same address used as the return address on the package. At the time of his arrest, Washington also had several business cards from Los Angeles and a piece of paper containing Dennis’s address in his wallet.
Washington and Dennis were indicted on one count of attempt to possess cocaine with intent to distribute in violation of 21 U.S.C. sec.sec. 841 and 846. After the district court [528]*528denied two motions to suppress, the district court severed the defendants’ eases for trial. At separate jury trials, Washington and Dennis were convicted, and the district court sentenced each defendant to seventy-eight months imprisonment and three years supervised release.
II. Discussion
A. Anticipatory Search Warrant
After discovering the cocaine in the Express Mail package but before delivering the package, the postal inspector obtained an anticipatory warrant to search the residence to which the package had been addressed. In the warrant application and supporting affidavit, the inspector stated that he discovered the package in the mail on its way to the residence to be searched and that he would perform a controlled delivery of the package before authorities executed the warrant. Additionally, because the residence to which the package was addressed was a two-story house consisting of two independent apartments, the warrant application and affidavit sought permission to search one of the apartments. However, . the application sought permission to determine which apartment would be searched at the time of the controlled delivery, based upon who accepted the package and into which apartment it was taken. Specifically, the affidavit requested:
... permission to search the first floor apartment if and only if an occupant of that apartment accepts delivery or opens the package or the second floor apartment if and only if an occupant of the second floor accepts delivery or opens the package.
Based upon this affidavit and application, the district court issued an anticipatory search warrant. Washington and Dennis contend that the warrant was invalid for two reasons. First, they argue that it neither specified the conditions precedent to execution on its face, nor attached the warrant affidavit containing those conditions to the warrant. Second, they contend that the warrant was not supported by probable cause because no independent nexus between the package and the defendants or the place to be searched existed.
We review legal determinations concerning the validity of a warrant and probable cause determinations de novo. Ornelas v. United States, — U.S. -, -, 116 S.Ct. 1657, 1663, 134 L.Ed.2d 911 (1996); United States v. Leidner, 99 F.3d 1423, 1425 (7th Cir.1996), cert. denied, — U.S. -, 117 S.Ct. 1434, 137 L.Ed.2d 542 (1997); United States v. Adames, 56 F.3d 737 (7th Cir.1995).
1. Conditions Precedent
Anticipatory warrants differ from other search warrants in that they are not supported by probable cause to believe that contraband exists at the premises to be searched at the time they are issued. In fact, a court issues an anticipatory warrant with the knowledge that contraband does not presently exist at the location to be searched. See Leidner, 99 F.3d at 1425. However, at the time a court issues an anticipatory warrant, probable cause exists to believe that contraband will be located at the premises to be searched after certain events transpire. Id. Thus, conditions precedent to the execution of an anticipatory warrant are integral to its validity. As the Second Circuit explained, probable cause to uphold an anticipatory search warrant exists when a government official presents independent evidence indicating that delivery of contraband will, or is likely to, occur and when the magistrate conditions the warrant on that delivery. United States v. Garcia, 882 F.2d 699, 702 (2d Cir.1989). In Garcia, a seminal case on anticipatory warrants, the court also recognized that warrants conditioned on future events present some potential for abuse. As such, the court cautioned that a magistrate issuing an anticipatory warrant should protect against premature execution “by listing in the warrant the conditions governing the execution which are explicit, clear, and narrowly drawn so as to avoid misunderstanding or manipulation by government agents.” Id. at 703-04.
Washington and Dennis contend that this cautionary language obligates the district court to list all conditions precedent to the execution of an anticipatory warrant on [529]*529the face of the warrant and that the anticipatory warrant issued in this case is invalid because it failed to list these conditions on its face. However, the Second Circuit has expressly rejected this argument. United States v. Moetamedi, 46 F.3d 225, 228-29 (2d Cir.1995). In Moetamedi, the court held that an anticipatory warrant need not state on its face the conditions precedent for its execution if the warrant affidavit contains “clear, explicit and narrowly drawn” conditions and the executing officers actually satisfy those conditions before executing the warrant. Id. at 229. The court reasoned that conditions precedent need not appear on the face of a warrant itself because the affidavit containing the conditions also will contain a sworn representation that the warrant will not be executed until the package is delivered and accepted. Id. (citing United States v. Tagbering, 985 F.2d 946, 950 (8th Cir.1993)). Even though a copy of the warrant affidavit was not attached to the warrant at issue in Moetamedi, the court upheld the warrant because the affidavit contained satisfactory conditions, the issuing magistrate accepted those conditions and the officers executing the warrant satisfied those conditions. Id.
We see no reason to depart from the Second Circuit’s interpretation of its own language. Indeed, our reasoning in an analogous Fourth Amendment case compels the same result. In United States v. Jones, 54 F.3d 1285, 1290-92 (7th Cir.), cert. denied, - U.S. -, 116 S.Ct. 263, 133 L.Ed.2d 186 (1995), we held that an affidavit supplying the requisite specificity needed to uphold a challenged warrant need not be physically appended to the warrant or explicitly incorporated by reference where the magistrate considered the affidavit in issuing the warrant and the officers complied with the affidavit when executing the warrant. In reaching this holding, we recognized that the particularity requirement must be applied in a manner that protects the subject of a search from the potential abuses of a general warrant while recognizing the realistic needs of law enforcement authorities. Id. at 1291. We concluded that under the circumstances of the case, relying on the affidavit to uphold the warrant would serve both those purposes. Id. Likewise, anticipatory warrants balance the need to protect the subjects of searches from the abuses of warrantless searches (under the exigent circumstances exception) and the practical needs of law enforcement personnel. See Leidner, 99 F.3d at 1425-26. Thus, relying on an affidavit to uphold an anticipatory warrant under circumstances similar to Jones would likewise promote the purposes behind the Fourth Amendment.
Here, the warrant application and affidavit contained satisfactory conditions. The face of the warrant stated that execution of the warrant was subject to the conditions stated in the affidavit.1 This evidences that the issuing judge read and considered the affidavit in issuing the warrant. The record also establishes that the officers complied with the conditions precedent in executing the warrant. For example, the postal inspector testified that the executing officers searched only the first floor apartment and conducted that search after Dennis accepted delivery of the package, Dennis and Washington took the package into the first floor apartment and the electronic beeper in the package sounded, indicating that someone had opened the package inside the apartment. Thus, the anticipatory warrant was valid even though it did not list the conditions precedent to execution on its face or append a copy of the supporting affidavit.
2. Nexus
As we have previously stated, because the contraband is not presently located at the place to be searched at the time an anticipatory warrant is issued and because probable cause depends on contingent future events, anticipatory warrants present greater potential for abuse than other warrants. Most notably, the government or a third party, acting either intentionally or accidentally, could mail a controlled substance to a residence to create probable cause to search the premises where it otherwise would not exist. [530]*530Leidner, 99 F.3d at 1430-31 (Diane P. Wood, J., concurring); United States v. Rey, 923 F.2d 1217, 1224-25 (6th Cir.1991) (Keith, J., concurring). Thus, to prevent law enforcement authorities from creating the circumstances which give rise to probable cause to search, the Ninth Circuit held that probable cause to support an anticipatory warrant does not exist unless a sufficient nexus between the parcel and the place to be searched exists. United States v. Hendricks, 743 F.2d 653, 654 n. 1, 655 (9th Cir.1984). For example, the Hendricks court explained that a showing that the contraband was on a “sure course” to the destination to be searched would demonstrate a sufficient nexus. Id. at 655. Other circuits, including this circuit, have adopted this “sure course” requirement. E.g. Leidner, 99 F.3d at 1427-28; United States v. Ricciardelli, 998 F.2d 8, 12 (1st Cir.1993); United States v. Dornhofer, 859 F.2d 1195, 1198 (4th Cir.1988).
Washington and Dennis argue that the government failed to establish that the Express Mail package was on a sure course to Dennis’s apartment because the government established only that a package containing contraband was mailed to the residence. They reason that that showing is insufficient because the government must establish either some connection between the residence to be searched and the package independent of the government-controlled delivery or some connection between the defendants and the package. We have not decided whether placing a package in the mail satisfies the sure course requirement. However, at least where the anticipatory warrant authorizes a search for and seizure of only the package containing the contraband, some circuits have held that placing contraband in the mail satisfies the sure course requirement. E.g. Dornhofer, 859 F.2d at 1198; United States v. Goodwin, 854 F.2d 33, 36 (4th Cir.1988); United States v. Hale, 784 F.2d 1465, 1468-69 (9th Cir.1986). On the other hand, other circuits have recognized that where a warrant authorizes a search for drug paraphernalia as well as the package containing the contraband, simply discovering that a package has been mailed to the residence to be searched may be insufficient to satisfy probable cause. Garcia, 882 F.2d at 704; United States v. Lawson, 999 F.2d 985, 988 (6th Cir.1993). These courts reason that authorities must demonstrate some other circumstances indicating that the sender intended the package to arrive at the residence to be searched and intended to send the package to the actual recipient.
Even if we were to adopt the latter approach, the warrant issued in this action would be valid. In both Garcia and Lawson, the courts upheld the warrants at issue because additional facts in the supporting affidavits gave rise to probable cause to search the residences. For example, in Garcia the court noted that someone had provided the drug couriers with the telephone number of the apartment to be searched before police stopped the couriers, that one of the couriers had delivered drugs to the residence in the past and that police had observed at least one person suspected of drug activity enter and leave the residence. 882 F.2d at 704. Likewise, in Lawson, the court held that all of the information contained in the affidavit “could reasonably lead a person to believe that an experienced trafficker in narcotics sent the package” and that “it was very likely that the address on the package was the one at which it was intended to arrive.” 999 F.2d at 988. In reaching this holding, the court noted that the amount of cocaine in the package — six ounces — was too large an amount to be sent on a whim and that the cocaine had been concealed in an attempt to avoid detection. Id.
Here, although Washington and Dennis maintain that the fact that the Express Mail package was mailed to the Decatur residence is the only fact in the supporting affidavit establishing probable cause, additional facts in the supporting affidavit also support a finding of probable cause. For example, the postal inspector testified that based upon his experience and drug trafficking intelligence he knew that drug traffickers were likely to use priority and Express Mail to ship narcotics. More importantly, he stated that he found sixteen ounces of cocaine in the package — a quantity of cocaine which like the six ounces in Lawson is too great an amount to be sent on a whim. Finally, he stated that investigators had connected Dennis to nar[531]*531cotics activities in the past. Thus, based upon all of the information in the affidavit, the district court could reasonably conclude that an experienced drug trafficker sent the package and that the address on the package was the one at which it was intended to arrive.
Moreover, we recognized in Leidner that all types of government-controlled deliveries are more likely to reach their destinations than other types of deliveries and that, consequently, a magistrate may conduct a lesser inquiry into the sure course requirement when a request for an anticipatory warrant is based upon a government-controlled delivery. Leidner, 99 F.3d at 1429. Thus, in a case such as this, where nothing in the record indicates that the contraband might not have been delivered to the residence to be searched, simply discovering the package in the mail stream and placing it back into the mail stream to effect a controlled-delivery should satisfy the sure course requirement. Id.
In an effort to sidestep this result, Washington and Dennis apparently argue that the government must establish a connection between the searched premises and the contraband which existed prior to the controlled delivery. For example, Dennis suggests a showing that he or one of his agents mailed the package in Los Angeles. However, we implicitly rejected this argument in Leidner. 99 F.3d at 1429-30. There, law enforcement authorities discovered 200 pounds of marijuana in a drug courier’s car during a traffic stop. The courier then identified the person to whom he was delivering the narcotics and agreed to cooperate in a controlled delivery. Id. Authorities obtained an anticipatory search warrant for the residence to which the marijuana was to be delivered, id., and the defendant, the recipient of the marijuana, challenged this warrant, contending that an anticipatory warrant is invalid unless the government demonstrates that the eontra-band was on a sure course to the residence before law enforcement authorities intercepted it. Id. at 1429 n. 7. Otherwise, the defendant reasoned, the courier could name anyone in an effort to lessen his punishment. Id. at 1429. We construed this as a challenge to the courier’s reliability and rejected it, adopting instead a “totality of the circumstances” approach similar to that which the Lawson and Garcia courts employed. Id. at 1429-30. We found that the totality of the circumstances in Leidner supported a finding of probable cause. In particular, we noted that authorities had corroborated certain portions of the courier’s allegations, that a local officer knew the courier and considered him rehable and that the courier made his statements against his penal interest. Id. at 1429-30. As we have stated above, the totality of the circumstances here, likewise, supports a finding of probable cause.2
B. Dennis’s Claims
1. Warrantless Stop
The postal inspector initially detained the Express Mail package and subjected it to a sniff by a drug detection dog because it possessed several characteristics which met the U.S. Postal Service’s narcotics package profile and which based upon his own experience were consistent with a package containing narcotics. Dennis contends that this initial warrantless detention violated his Fourth Amendment rights. The Supreme Court has recognized that individuals have a Fourth Amendment right to be free from unreasonable searches and seizures of items they place in the mail. United States v. Van Leeuwen, 397 U.S. 249, 251, 90 S.Ct. 1029, 1031, 25 L.Ed.2d 282 (1970). However, if law enforcement authorities possess reasonable suspicion to believe that a package contains contraband, they may detain that package for a reasonable length of time while investigat[532]*532ing the package. Id. at 252-53, 90 S.Ct. at 1032-33. Thus, we may uphold the detention here if the postal inspector reasonably suspected that the package contained contraband and if the detention lasted for a reasonable duration. United States v. Mayomi, 873 F.2d 1049, 1054 (7th Cir.1989).3
We review a determination of reasonable suspicion de novo. Ornelas v. United States, — U.S. -, -, 116 S.Ct. 1657, 1663, 134 L.Ed.2d 911 (1996). However, we review findings of historical fact for clear error only and give due weight to the inferences that resident judges and local law enforcement officers draw from those facts. Id. Here, the postal inspector articulated several factors which aroused his suspicion. He also stated that these factors met some of the elements of the Postal Service’s narcotics package profile. Thus, on appeal, both parties rely on the validity or invalidity of the profile in arguing for or against reasonable suspicion. For example, Dennis maintains that the postal authorities lacked reasonable suspicion to detain his package because the profile criteria are too vague and unreliable, while the government asserts that the fact that the Express Mail package met the profile supports a finding of reasonable suspicion.
However, the profile itself is irrelevant to a reasonable suspicion determination. The mere fact that certain characteristics that a law enforcement officer observes fit a profile will not establish reasonable suspicion. United States v. Hanson, 801 F.2d 757, 762 (5th Cir.1986); see Reid v. Georgia, 448 U.S. 438, 440-41, 100 S.Ct. 2752, 2753-54, 65 L.Ed.2d 890 (1980) (rejecting appellate court’s finding of reasonable suspicion based solely on the fact that the defendant fit a drug courier profile). Likewise, the mere fact that the characteristics which the authorities observe may be set forth in a profile does not detract from the evidentiary significance of those characteristics. United States v. Sokolow, 490 U.S. 1, 10, 109 S.Ct. 1581, 1586, 104 L.Ed.2d 1 (1989). Instead, in reviewing a reasonable suspicion determination, we require law enforcement authorities to articulate the specific characteristics exhibited by the person or object to be detained which aroused the authorities’ suspicion in the particular ease before us, and we determine whether those characteristics would reasonably arouse suspicion under the circumstances presented in the ease. See Sokolow, 490 U.S. at 10, 109 S.Ct. at 1586; Hanson, 801 F.2d at 762, Wayne R. LaFave, Search and Seizure § 9.4(e) at 174 (3d ed. 1996).
Here, the postal inspector stated that the package aroused his suspicion because it was heavily taped, had been sent from a private person to another private person, had been mailed from Los Angeles, a city known to be a source city for narcotics distribution, and had been mailed from a zip code different than the zip code listed in the return address. The postal inspector explained that based on his five years of experience as a narcotics investigator and based upon the narcotics package profile, these factors were consistent with characteristics of other packages found to contain contraband. For example, he explained that because of its high cost, only about five percent of all Express Mail is personal correspondence and that because of its speed and reliability and because the postal service provides a free telephone tracking service, drug traffickers frequently use the service to send personal correspondence containing contraband. Thus, he concluded that personal correspondence sent via Express Mail is likely to contain contraband. Under these circumstances, the postal inspector’s suspicion was reasonable and justified detaining the Express Mail package. See United States v. Lux, 905 F.2d 1379 (10th Cir.1990) (finding reasonable suspicion where the package met three unspecified factors in the postal service’s narcotics package profile) aff'g United States v. Hill, 701 F.Supp. 1522, 1528 n. 5 (D.Kan.1988) (the package’s size, shape and [533]*533destination met the profile, the sender hand-wrote the label and the sender had an unusual return name/address).
Dennis also contends that the factors which the postal inspector articulated are insufficient to arouse reasonable suspicion because each of the factors is consistent with packages which do not contain contraband. However, in certain circumstances wholly lawful conduct may justify an officer’s suspicion that criminal activity is afoot. Sokolow, 490 U.S. at 9, 109 S.Ct. at 1586 (quoting Reid, 448 U.S. at 441, 100 S.Ct. at 2754); see, e.g., Terry v. Ohio, 392 U.S. 1, 22, 88 S.Ct. 1868, 1880, 20 L.Ed.2d 889 (1968) (reasonable suspicion based on “a series of acts, each of them perhaps innocent” but when “viewed together warranted further investigation”). Moreover, circumstances which appear innocent to the outside observer may suggest criminal activity to experienced law enforcement personnel, and in determining whether reasonable suspicion exists, law enforcement authorities may assess these circumstances in light of their experience. United States v. Cordell, 723 F.2d 1283, 1285 (7th Cir.1983); see United States v. Sharpe, 470 U.S. 675, 682-83 n. 3, 105 S.Ct. 1568, 1573-74 n. 3, 84 L.Ed.2d 605 (1985) (“[T]aken together as appraised by an experienced law enforcement officer, [the articulated factors] provided clear justification to stop the vehicles and pursue a limited investigation.”). Here, admittedly, any one of the factors which the postal inspector articulated may be found in innocent mailings as well as packages containing contraband. However, the confluence of all of these factors in a single package when appraised by the postal inspector, an experienced narcotics investigator, amounted to reasonable. suspicion that the Express Mail package may have contained contraband and justified the investigatory detention.
At some point in time, however, a detention of mail will extend from a stop to a seizure requiring probable cause to support it rather than mere reasonable suspicion. See Sharpe, 470 U.S. at 685, 105 S.Ct. at 1574. Thus, we also must determine whether the inspector detained the package for an unreasonably long period of time before obtaining a search warrant. Mayomi, 873 F.2d at 1053-54. Brevity of a detention is an “important factor” in determining whether it may be justified by reasonable suspicion only. Place, 462 U.S. at 709, 103 S.Ct. at 2645. However, we may also consider whether the police diligently pursued their investigation. Id. Accordingly, in Mayomi, we determined that detaining one of the letters at issue for less than one day was a de minimis intrusion that did not implicate the defendant’s Fourth Amendment rights and that detaining the remaining two letters for forty-eight hours, over a weekend, so that the inspector could subject them to a canine sniff was brief enough to be sustained by reasonable suspicion. 873 F.2d at 1054.
Here, the record does not clearly reveal when the package was placed in the mail. (A photocopy of the Express Mail label appears to be postmarked August 9,1995.) However, the record clearly shows that the postal inspector discovered the Express Mail package in the mail and detained it at some time on August 10, 1995. By 6:05 p.m. on that same day, the inspector had completed the canine sniff and obtained a search warrant to open the package. Additionally, the package appears to have been delivered on time, and the record indicates that the postal inspector was diligent in his investigation. Thus, any detention was less than forty-eight hours and lasted only as long as necessary to subject the package to a canine sniff. As such, the postal inspector’s reasonable suspicion justified the stop, and the search comported with the standards set forth in Van Leeuwen.
2. Discovery Rule Violations
In between Dennis’s trial and Washington’s trial, the government obtained the results of a fingerprint analysis which found both Washington’s and Dennis’s fingerprints on the outside of the Express Mail package. The government did not learn of these test results until after Dennis’s trial. Consequently, the government failed to disclose these results to Dennis before trial but also necessarily did not use this evidence in its [534]*534case-in-chief against Dennis.4 Dennis contends that because the government could have learned about the results using reasonable efforts, its failure to learn about the results and disclose them to Dennis violates its pre-trial discovery requirements under Federal Rule of Criminal Procedure 16. He reasons that because the omission substantially prejudiced him, he is entitled to a new trial. The district court rejected this argument when Dennis raised it in his post trial motions, and so do we.
Rule 16 provides that a court may, but is not required to, impose sanctions against a party who violates its disclosure requirements. United States v. Jackson, 51 F.3d 646, 651-52 (7th Cir.1995). Those sanctions are left to the court’s discretion, and we will not second guess the court’s decision absent abuse of that discretion. Id. Thus, a new trial is warranted only if the government violated Rule 16 and the remedy offered by the district court was inadequate to provide the defendant with a fair trial. Id.; United States v. Mounts, 35 F.3d 1208, 1217 (7th Cir.1994).
We fail to see how the fingerprint evidence would have helped Dennis, and the government did not use the evidence in its case. Thus, we are uncertain that the government violated Rule 16. However, the government has conceded that it violated the rule. Accordingly, we will analyze whether the district court abused its discretion in refusing to sanction the government. Because neither party learned about the fingerprint evidence ■until after the trial, the only sanction available to the district court to remedy the violation was a new trial. However, the district court refused to impose this sanction, finding that in light of the “overwhelming” evidence of guilt, the fingerprint evidence would not have affected the outcome of the case. In reaching this holding, the court noted that a videotape entered into evidence showed Dennis receiving the package, putting it down while he surveyed the area to determine if any police officers were present and picking up the package and bringing it into the apartment. The court also referred to testimony that Dennis was attempting to flush the cocaine down the toilet at the time the police apprehended him and to the fact that Dennis’s fingerprints were on the box along with Washington’s. In light of this evidence, we agree with the district court that the fingerprint evidence would not have affected the outcome of the trial and that, accordingly, Dennis was not prejudiced by the government’s failure to disclose it to him. Because Dennis received a fair trial, the district court did not abuse its discretion in refusing to impose sanctions, and a new trial is not warranted.
C. Washington’s Claim
Washington argues that the government presented insufficient evidence at trial to sustain the guilty verdict against him. In challenging the sufficiency of the evidence, Washington must overcome a formidable hurdle. United States v. Crowder, 36 F.3d 691, 695 (7th Cir.1994). We will uphold a conviction if, when viewed in the light most favorable to the government, the evidence establishes that any rational trier of fact could have found the essential elements of a crime beyond a reasonable doubt, and we will not overturn a jury’s verdict unless the record contains no evidence, regardless of how it is weighed, from which the jury could find guilt beyond a reasonable doubt. Id.; United States v. Van Wyhe, 965 F.2d 528, 531 (7th Cir.1992). Moreover, we will not reweigh evidence or judge the credibility of witnesses. Van Wyhe, 965 F.2d at 531.
A jury convicted Washington of attempting to possess cocaine with the intent to distribute it. This charge required the government to prove that Washington acted with specific intent to commit the underlying offense and that Washington took a substantial step towards committing the underlying offense. United States v. Cea, 914 F.2d 881, 887 (7th Cir.1990). The government presented evidence that Washington was present when Dennis accepted delivery of the package and accompanied Dennis into the apartment with the package, that Washington at[535]*535tempted to flee when the police executed the search warrant and that Washington produced a false I.D. when police apprehended him. Additionally, the false I.D. which Washington produced listed the return address on the package as Washington’s address, and at the time of his arrest, Washington had in his wallet business cards from Los Angeles and a piece of paper with Dennis’s address written on it. The government introduced all of this into evidence. Finally, Dennis testified that Washington told him that a package with “something sweet” in it was coming to his house and that Washington opened the package after Dennis brought it inside the house. Clearly, a rational jury could find beyond a reasonable doubt that Washington acted with specific intent to possess cocaine with the intent to distribute it and that Washington took a substantial step toward committing this crime based on this evidence.
Washington maintains that Dennis’s testimony was “vague, waffling, and constantly impeached” and, therefore, is insufficient to sustain the verdict. (Washington’s Br. at 13-14). He reasons that without Dennis’s testimony the government presented no evidence from which a jury could find beyond a reasonable doubt that Washington took any substantial step toward possessing cocaine. Even if we were to agree with Washington that the government presented no other sufficient evidence, we may not discount Dennis’s testimony. Absent extraordinary circumstances, we cannot reevaluate a witness’s testimony to determine its credibility. Crowder, 86 F.3d at 696. Thus, even when the defendant’s conviction rests on his accomplice’s uncorroborated testimony, we must uphold the verdict unless the testimony is incredible as a matter of law. Id. A witness’s testimony is incredible as a matter of law only if it is unbelievable on its face. Id. at n. 1. Testimony is unbelievable on its face if it is physically impossible for the witness to observe that which he claims to have observed or if it is impossible under the laws of nature for the occurrence to have taken place at all. Id. Dennis’s testimony in the instant action is not incredible as a matter of law. While his testimony may have been inconsistent and self-serving, nothing in his testimony is impossible, nor did he testify as to any events which he could not have observed. The jury was aware of Dennis’s role in the crime and inconsistencies between his in-court testimony and out-of-court statements and was entitled to determine Dennis’s credibility and weigh his testimony as it saw fit. Based upon his testimony and the government’s other evidence, it found Washington guilty. We may not reweigh Dennis’s testimony. Thus, we affirm the verdict.
Moreover, in arguing that the government presented no sufficient evidence aside from Dennis’s testimony, Washington discounts the postal inspector’s testimony that Washington was present at the apartment when the box was delivered and the I.D. and business cards which were admitted into evidence. While conceding that these items “suggest[ ] the possibility of his guilt,” Washington maintains that this evidence is insufficient to sustain the verdict because “other explanations suggesting innocence are plausible.” (Washington’s Br. at 13). However, the government need not present evidence that excludes every reasonable hypothesis of innocence so long as the total evidence permits a conclusion of guilt beyond a reasonable doubt. The evidence which the government presented to the jury met this burden. Thus, we affirm Washington’s conviction.
III. Conclusion
Both defendants were well represented, but for the foregoing reasons, the convictions of Dennis and Washington must be AfFIRMED.