The U.S. Attorney’s Office in Kansas has stopped cooperating with an investigation into the taping of attorney-client meetings and phone calls at the pretrial detention facility in Leavenworth, according to the special master looking into the matter.

The decision by the office is likely to heighten suspicions by criminal defense lawyers that the U.S. Attorney’s Office is concealing information about the tapings from them.

Many of them have filed motions to dismiss cases against their clients on the grounds their Sixth Amendment rights were violated.

And at least two class action lawsuits have been filed by attorneys and former detainees over the tapings. Both lawsuits seek at least $5 million in damages from the operator of the prison, CoreCivic Inc. (formerly known as Corrections Corporation of America), and the company that provides the prison with phone services, Securus Technologies.

Both companies have denied wrongdoing. And in his latest report to the court, the special master, David R. Cohen, commends them for their cooperation.

In that report, Cohen says that, in contrast to the companies, he received a 24-page letter last month from the U.S. Attorney’s Office stating that it will no longer provide him with information and documents he is seeking as part of his investigation.

The letter was written by Steven D. Clymer, a federal prosecutor in New York who was appointed to act as the contact with Cohen after the U.S. Attorney’s Office in Kansas concluded it might have a conflict.

The letter cites a variety of reasons for declining Cohen’s requests for information, including the assertion that there is no evidence suggesting there were any Sixth Amendment right-to-counsel violations.

“More importantly,” Clymer wrote, “there is no evidence that any defendant indicted in the Black case suffered a violation of his or her Sixth Amendment right to counsel or infringement of his or her attorney-client privilege.”

Clymer was referring to the case that led to the disclosures that some attorney-client conversations were audio- and videotaped at the Leavenworth facility. The case, which was filed by the U.S. Attorney’s office last year, accuses inmates and guards at the facility of smuggling drugs into the prison.

Moreover, Clymer states in his letter, “There is no evidence that the recording of attorney-inmate meetings or outgoing inmate telephone calls to attorneys was conducted at the direction of the OUSA (U.S. Attorney’s Office).”

Cohen, in his report to U.S. District Judge Julie Robinson, who appointed him, says he was surprised by Clymer’s position.

“From the Special Master’s perspective, that the OUSA may have valid bases upon which to refuse production of information does not mean it is wise to do so,” Cohen wrote in his report, his first since Robinson expanded the scope of his investigation to look into whether federal prosecutors obtained and used such recordings.

“As the Special Master noted earlier, ‘there is a widespread undergrowth of mistrust between the Office of the United States Attorney for the District of Kansas and defense counsel…’”

Cohen goes on to say that the decision not to produce responsive information “is a drawing of shades against sunlight; this will not ameliorate any mistrust from the defense bar.”

In fact, Cohen says, it may even be against the OUSA’s own interests. He says his investigation to date suggests only one instance where the U.S. Attorney requested video recordings of meetings between inmates and their attorneys “and the OUSA did not actually view any such meeting.”

The federal public defender, which led the charge for an investigation into whether prosecutors violated the attorney-client privilege, is expected to file a response to Cohen’s report this week.

Dan Margolies is a senior reporter and editor for KCUR. You can reach him on Twitter @DanMargolies.