DAVID A. NELSON, Circuit Judge.
Pursuant to the Freedom of Information Act — a statute which, subject to certain exceptions, makes federal government records available to anyone who asks for them— plaintiff Brian Dickerson requested the release of records on an investigation eonduet-ed by the Federal Bureau of Investigation into the disappearance of Jimmy Hoffa, former president of the Teamsters Union.
Citing 5 U.S.C. § 552(b)(7)(A), which exempts from disclosure “records or information compiled for law enforcement purposes, but only to the extent that the production of such law enforcement records or information ... could reasonably be expected to interfere with enforcement proceedings,” the government denied the request. Mr. Dickerson brought suit in the Eastern District of Michigan to compel the Department of Justice to produce the records. The district court (La Plata, J.) ultimately decided that production was not required.
In making its decision the district court focused on the question whether a “concrete prospective law enforcement proceeding”1 .could still be discerned — ie., whether there was still a reasonable chance that someone would be prosecuted in connection with Mr. Hoffa’s disappearance. Based on affidavits of several FBI officials and an in camera review of FBI file documents assembled for the purpose of briefing one of the affiants on the status of the investigation, the district court found that “the investigation into Hoffa’s disappearance is active and continuing, with the clear direction of future criminal proceedings being instituted.” The court further found that disclosure of the requested documents could reasonably be expected to interfere with such proceedings. The court made these findings without having required the government to provide a document-by-document analysis of the files.
The issues presented on appeal are (1) whether the district court abused its discretion in not insisting on a full document-by-document analysis and in limiting its in camera review to the briefing materials; (2) whether the district court dealt correctly with the factual side of the ease; and (3) whether the district court ought to have found that at least some non-public portions of the investigatory files were not protected [1428]*1428from disclosure. Resolving each' of these issues in favor of the government, we shall affirm the judgment of the district court.
I
Jimmy Hoffa disappeared in Detroit, Michigan, on July 30, 1975. It is widely believed that he was abducted and killed. Mr. Hoffa’s disappearance led to an FBI investigation that has not, to date, resulted in any criminal proceedings being brought.
The investigation is documented in two large files, one maintained in the FBI’s field office in Detroit and the other at FBI headquarters in Washington. At the time with which we are concerned in this proceeding the headquarters file consisted of 67 volumes and the field office file consisted of 332 volumes.
On July 25, 1989, counsel for the Detroit Free Press, a newspaper that employs plaintiff Dickerson in an editorial capacity, sent sweeping Freedom of Information Act requests on the Hoffa investigation to Justice Department and FBI officials in Detroit and Washington. When the requests were denied, Mr. Dickerson sued the Department of Justice under 5 U.S.C. § 552(a)(4)(B), which gives federal district courts jurisdiction to order the production of agency records withheld improperly. This section of the statute, which places the burden of sustaining nondisclosure on the government, directs the court to determine the matter de novo. It also provides that the court “may examine the ... agency records in camera to determine whether such records or any part thereof shall be withheld under any of the exemptions set forth in [5 U.S.C. § 552(b)]....”
The Department of Justice filed an answer admitting that there were no pending criminal proceedings directly relating to Mr. Hoffa’s disappearance, but asserting that no documents had been improperly withheld. Both parties subsequently moved for summary judgment.
The plaintiffs summary judgment motion was accompanied by newspaper articles referring to á statement by Kenneth P. Walton, a retired head of the FBI’s Detroit field office, to the effect that although he knew who had murdered Jimmy Hoffa, there would never be a prosecution because of the government’s unwillingness to disclose confidential sources. The Justice Department filing was accompanied by “declarations,’’ or affidavits, in which two FBI headquarters officials, Angus B. Llewellyn and Jim E. Moody, attested that the Hoffa investigation was still pending.
The Llewellyn declaration went on to give a general description of the contents of the investigatory files, categorizing the records by source or function. The declaration also sought to explain why law enforcement records contained in the files were exempt from production not only under subsection (7)(A) of 5 U.S.C. § 552(b), but also under subsection (7)(C) (exempting such records if they “could reasonably be expected to constitute an unwarranted invasion of personal privacy”); subsection (7)(D) (exempting them if they “could reasonably be expected to disclose the identity of a confidential source”); and subsection (7)(E) (exempting them if they “would disclose techniques and procedures for law enforcement investigations or prosecutions ... if such disclosure could reasonably be expected to risk circumvention of the law”).
The Moody declaration focused on the (7)(A) exemption. The declaration explained, among other things, that
“The files responsive to plaintiffs [Freedom of Information Act] request contain documents detailing the FBI’s theories regarding the case, investigative leads we’re pursuing (and those we don’t consider worthy of pursuit), information furnished by confidential sources, information indicating whom the prime suspects are considered to be, techniques being utilized by the FBI in this investigation, interviews of third parties and cooperating witnesses, results of laboratory and polygraph examinations, and suggestions as to how to proceed with this investigation.”
The Moody declaration stated that the FBI was continuing its efforts to develop information for use in criminal proceedings, and the declaration sought to show why production of [1429]*1429the records could reasonably be expected to interfere with such proceedings.
In January of 1991 the district court denied both of the motions for summary judgment on the ground that there was a material issue of fact concerning the prospect of future enforcement proceedings. The Justice Department moved for reconsideration, supporting its motion with a declaration executed by William M. Baker, the Assistant Director of the FBI in charge of the agency’s Criminal Investigation Division.
Mr. Baker declared under penalty of perjury that it was his responsibility to determine whether the investigation into the Hoffa disappearance should be pursued; that in his judgment the investigation warranted the continuing efforts of the FBI; that he had allocated continued FBI resources to the investigation; that he believed “that the person(s) responsible for Mr. Hoffa’s disappearance can be identified and prosecuted;!’ and that public disclosure of the information in the Hoffa file could reasonably be expected, for reasons specified in the declaration, to interfere with enforcement proceedings against those responsible for the disappearance. Mr. Baker further declared that the statement attributed to the former field office head “did not reflect and does not reflect official FBI policy.”
In response to the motion for reconsideration plaintiff Dickerson filed a reply brief stating that Mr. Baker’s declaration was essentially identical to one he had filed in a Freedom of Information Act suit brought in a federal district court in Missouri by Mr. Hoffa’s daughter, Barbara Crancer. The brief pointed out that the declaration had not dissuaded the district court in Missouri from ordering the government to submit a Vaughn index on the smaller of the two Hoffa files,2 and it noted that FBI Director William Sessions had testified before a Senate Subcommittee that it is “doubtful” that the government will ever have sufficient evidence to bring to trial those responsible, for Mr. Hoffa’s disappearance.3'
Plaintiff Dickerson’s reply brief further advised the court that the Missouri proceedings had disclosed the existence of two categories of documents that might quickly reveal the status of the Hoffa investigation: documents containing the results of high level strategy conferences, with synopses of the investigation to date, and memoranda updating the Director of the FBI on the status of the investigation. The plaintiffs brief suggested that the court conduct an in camera review of all documents in these two categories. Since the Missouri court had already ordered the Justice Department to prepare a Vaughn index on the 68-volume file from FBI headquarters in Washington, plaintiff Dickerson suggested that the Department should be ordered to produce a copy of that index as well.
In the meantime, plaintiff Dickerson had served notice 'of the depositions of FBI Director Sessions and declarants Llewellyn, Moody and Baker, and the Justice Department had moved for a stay of discovery. The motion was referred to a magistrate judge, who conducted two telephone conferences on the matter.
In the course of the first conference the Justice Department indicated a willingness to go through the headquarters file and segre[1430]*1430gate, for in camera review by the court, all documents in the two categories singled out by the plaintiff. Government counsel later confirmed with declarant Moody, Chief of the FBI’s Organized Crime Unit, that such documents had not yet been physically segregated. Mr. Moody disclosed to counsel, however, and counsel disclosed at the second telephone conference with the magistrate judge, that Moody already had a file of documents, culled from the field office records in Detroit, that contained an update on the Hoffa investigation. This file had recently been assembled on Mr. Moody’s own initiative to prepare him to testify if he should be ordered to give his deposition. The Moody file had not been put together with the idea of turning it over to the court for in camera review, counsel explained, but the government offered to make it available to the court for that purpose, along with all documents in the two categories specified by the plaintiff.
The magistrate judge expressed an interest in keeping the scope of any in camera review manageable, and counsel for plaintiff Dickerson agreed that the district judge would be more likely to undertake such a review if the quantity of materials were not excessive. The telephone conference led to an order in which the magistrate judge directed that the Moody file be sent to Michigan for possible in camera inspection by District Judge La Plata. The plaintiffs request to depose the four FBI officials was deferred in the meantime.
Judge La Plata concluded that with the addition of Assistant Director Baker’s declaration, the declarations alone might be sufficient. In view of the testimony before the Senate subcommittee, however, and in view of the length of time that had elapsed since Mr. Hoffa’s disappearance, Judge La Plata elected to review the Moody file (consisting of some 335 pages) in its entirety.
Having completed a careful and thorough review of the Moody file in camera, the court expressed itself as “satisfied beyond any doubt” that the investigation was active, that it was continuing, and that it was directed toward the institution of criminal proceedings. Because the court likewise found that disclosure of the documents sought by plaintiff Dickerson and his newspaper could reasonably be expected to interfere with enforcement proceedings, the court entered summary judgment in favor of the Department of Justice. A subsequent motion for reconsideration was denied, and this appeal followed.
II
Law enforcement records cannot “reasonably be expected to interfere with enforcement proceedings,” it has been suggested, unless there is at least “a reasonable chance that an enforcement proceeding will occur....” Nevas v. Dept. of Justice, 789 F.Supp. 445, 448 (D.D.C.1992).4 We agree, and we turn first to the procedure followed by the district court in preparing itself to determine the likelihood that enforcement proceedings might still occur in the Hoffa ease. (The court’s determination of the likelihood that disclosure of the requested documents might interfere with any such proceedings also has a procedural aspect, and we shall touch on this at the same time.)
Although requested to follow the lead of the district court in Missouri in ordering the compilation of a Vaughn index on the FBI headquarters file, Judge La Plata did not do so. Plaintiff Dickerson maintains that the court committed reversible error in granting the government’s summary judgment motion without having had the benefit of such an index.
Depending on the nature of the case, the use of a Vaughn index may have obvious advantages from the perspective of one or another of the litigants or from the perspective of the courts. See, for example, Ingle v. [1431]*1431Dept. of Jtistice, 698 F.2d 259 (6th Cir.1983), where we indicated that a Vaughn index makes the playing field more nearly level for the party seeking disclosure, facilitates effective appellate review, and may obviate any need for the courts to review documents in camera. In the context of a ease that did not involve exemption (7)(A), we have said that a Vaughn index should be obtained in “most” Freedom of Information Act cases. Osborn v. Internal Revenue Service, 754 F.2d 195, 197 (6th Cir.1985).
As we subsequently explained in a Vaughn decision of our own, however, Osborn created no hard and fast rule with respect to Vaughn indices as such. Vaughn v. United States, 936 F.2d 862, 867 (6th Cir.1991). The government must provide sufficient information in sufficient detail to enable the court “to make a reasoned, independent assessment of the claim of exemption,” but no particular method of doing so is mandated; “[a] court’s primary focus must be on the substance, rather than the form, of the information supplied by the government to justify withholding requested information.” Id. The Supreme Court has consistently taken what it terms “a practical approach” to Freedom of Information Act matters, see John Doe Agency v. John Doe Corp., 493 U.S. 146, 157, 110 S.Ct. 471, 477, 107 L.Ed.2d 462 (1989), and this circuit tries to do the same.
Where exemption (7)(A) is concerned, as a practical matter, it is often feasible for the courts to make “generic determinations” about interference with enforcement proceedings. See NLRB v. Robbins Tire & Rubber Co., 437 U.S. 214, 223-24, 98 S.Ct. 2311, 2317-18, 57 L.Ed.2d 159 (1978).5 In many (7)(A) cases, at least, affidavits of the sort presented by the government here would seem to provide an adequate basis for making such determinations.
The case at bar may be somewhat unusual in that here the district court was initially uncertain whether an actual enforcement proceeding was still being contemplated and whether the “purpose and point” of the investigation that generated the records in question had “expired.” See Robbins Tire, 437 U.S. at 232, 98 S.Ct. at 2322, referring to legislative history indicating that “with the passage of time, ... when the investigation is all over and the purpose and point of it has expired, [disclosure] would no longer be an interference with enforcement proceedings and there ought to be disclosure.” But insofar as the question to be resolved by the courts is whether actual enforcement proceedings are still being contemplated, it does not seem to us that valuable time should normally have to be spent on the preparation and analysis of a Vaughn index. As a practical matter, affidavits by people with direct knowledge of and responsibility for the investigation usually ought to suffice.
Here the district court believed that the government’s affidavits might be sufficient standing alone to support a finding on whether the point and purpose of the investigation had expired, but the court nonetheless felt the need for a reality check of some kind. The Moody file seemed like a sensible place to start, and we think it was clearly within the court’s discretion to begin there. If the Moody file had turned out not to be helpful, the court could obviously have moved on to an in camera inspection of the two groups of [1432]*1432documents that both parties had suggested the court might wish to examine. After reviewing all of the documents in the Moody file, however, the court concluded that there was no need to go further. We too have reviewed the Moody file in its entirety, and we see no abuse of discretion in the district court’s decision on this score.
Plaintiff Dickerson argues that the' decision to review only documents “hand-picked” by the government deprived him of the benefits of the adversary process. But the'materials in the Moody file were selected, as we have seen, for briefing Mr. Moody on the status of the investigation, and not for submission to the court for review by it in camera. The idea of a court review of the Moody file in isolation originated with the magistrate judge, not with the government. The review process was necessarily non-adversarial, to be sure, but the process would have been equally non-adversarial if the documents under review had included the additional materials the government had said it was willing to turn over to the court.
The approach developed by the magistrate judge was designed in part to avoid a situation in which the district judge might have felt constrained to review more documents in camera than he would have wanted to see. This approach makes sense to us. The adversaries could, and did present arguments on the sufficiency of the affidavits that formed the government’s main line of defense,6 and review of any documents in camera might well have been deemed superfluous; we think it was reasonable for the magistrate judge to offer Judge La Plata the documents that had already been segregated, and we think it was reasonable for Judge La Plata to decide, after reviewing them, that he had seen all he needed to see in order to make a proper decision.
III
A
The district court was correct, we believe, in its finding on the likelihood of a criminal prosecution being brought.
It is clear, as we read the record, that the Hoffa investigation remains active. In the judgment of Assistant Director Baker — the person whose responsibility it is to- determine whether the investigation should still be pursued, and, if so, what FBI resources should be devoted to it — the investigation warrants the FBI’s continued efforts to bring to trial those responsible for Mr. Hoffa’s disappearance.
Mr. Baker has allocated continued FBI resources to the Hoffa investigation, according to his declaration, and the declaration says that the investigation “is ongoing and still absorbs FBI management and field agent resources on a regular basis.” The documents in the Moody file , are consistent with Mr. Baker’s representation that the Hoffa investigation remains active.
The fact that the investigation is continuing does not mean that a prosecution will definitely be brought, of course, but the Baker declaration says that FBI criminal investigations often result in enforcement proceedings many years after the crimes were committed. “[W]ith the passage of time,” Mr. Baker continues, “persons with knowledge of Mr. Hoffa’s disappearance may feel more free to disclose critical information to law enforcement officers.” Attesting to a “belief that the person(s) responsible for Mr. Hoffa’s disappearance can be identified and prosecuted,” Mr. Baker says that he “would not knowingly permit scarce FBI resources to be devoted to a futile investigation.”
FBI retiree Walton and Executive Assistant Director Revell may consider it doubtful whether anyone will ever be brought to trial in the Hoffa case, and they may be right. Neither of them is responsible for deciding whether it is worthwhile to continue the investigation, however, and the official who does have that responsibility — -Assistant Director Baker — obviously believes that there is still a reasonable prospect of a prosecution being brought. No court is likely to be able to match Mr. Baker’s expertise on that kind [1433]*1433of question, and, like the district court, we are disposed to' defer to his judgment.
B
The district court was also correct, we believe, in its finding that production of the records sought by plaintiff Dickerson could reasonably be expected to interfere with a future prosecution.
In some contexts, the Supreme Court has said, the most obvious risk of interference with enforcement proceedings is that witnesses will be coerced or intimidated into changing their testimony or not testifying at all. Robbins Tire, 437 U.S. at 239, 98 S.Ct. at 2325. The declarations of Messrs. Llewellyn and Moody both demonstrate that witness intimidation is a genuine concern in the Hoffa investigation — an investigation that the FBI has designated a “Racketeering Influenced and Corrupt Organization-La Cosa Nostra Labor Racketeering Investigation.” If the perpetrators of the crime knew what investigative leads the FBI is pursuing, who the prime suspects are, and the nature of the evidence gathered to date, as one of the affidavits explains, they “could take steps to destroy or tamper with evidence, intimidate witnesses or construct a false alibi.... ”
In organized crime investigations such as this one, moreover, it has been the experience of declarant Moody, the chief of the Organized Crime Section of the FBI’s Criminal Investigation Division, that informants can provide information critical to the successful conclusion of the investigation. Public disclosure of the Hoffa investigation files, Mr. Moody has declared, would discourage such individuals from coming forward.
Another important issue, particularly in homicide cases, has to do with the corroboration of evidence. Verification of statements given by future witnesses becomes harder, Mr. Moody has indicated, where the factual information developed in the investigation has entered the public domain.
In addition, the record before us shows that the Hoffa files contain information regarding other pending and prospective criminal proceedings. The prospect of interference with such enforcement proceedings is not without significance.
Although the government has the burden of showing that production of the records could reasonably be expected to interfere with enforcement proceedings, the mere fact that the burden of justifying non-disclosure rests with the government does not illuminate the question of how heavy the burden is. See Robbins Tire, 437 U.S. at 224, 98 S.Ct. at 2318. Having regard to the important public interest that exemption (7)(A) was designed to protect, having regard to the fact that the language of the exemption has been broadened by Congress to protect records that “could” be expected to interfere, as opposed to records that “would” interfere, and having regard to the obvious risks that public disclosure of these active investigation files would entail, we agree with the district court that the burden with respect to interference has been met in this case.
IV
The Llewellyn declaration characterizes the documents in the Hoffa investigation files as follows:
“Documents setting forth leads to be conducted.
Documents containing information received from confidential informants.
Information and documents provided by local law enforcement.
Interviews of third parties and cooperating witnesses.
Public source information such as newspaper clippings and press releases.
Public and sealed court documents.
Laboratory reports setting forth results of examinations.
Polygraph worksheets and reports.”
To the extent that public source information and public judicial materials are included in the files, the government has agreed to make the relevant documents available to plaintiff Dickerson. All that is in controversy here is the non-public portions of the files.
Plaintiff Dickerson candidly acknowledges, in a footnote toward the end of his principal brief, that it is open to the government to justify the assertion of a (7)(A) exemption on a “category-of-document” basis rather than [1434]*1434by proceeding document by document. He points out, however, that there is no blanket exemption for investigatory files as such, and he argues that we should at least remand the case with instructions that the government be required to segregate and produce all nonexempt material. In support of this suggestion he quotes the last sentence of 5 U.S.C. § 552(b), which says that “[a]ny reasonably segregable portion of a record shall be provided to any person requesting such record after deletion of the portions which are exempt under this subsection.”
It is doubtless true that by deleting large portions of the information contained in the Hoffa files, the government could render whatever was left useless to any law-breaker. (And useless to plaintiff Dickerson and his newspaper, we might add.) But the words “reasonably segregable” must be given a reasonable interpretation, particularly where information or records compiled for law enforcement purposes are concerned. On the record before us we do not believe that the prospects for finding any “reasonably seg-regable” non-public portions of the Hoffa files that could properly be made public are such as to justify the remand that plaintiff Dickerson seeks.
The judgment of the district court is AFFIRMED.