KANSAS CITY, Kan. (AP) — The special master looking into the taping of attorney-client meetings and phone calls at the pretrial detention facility in Leavenworth, Kansas, says in a new report that the U.S. Attorney’s office in Kansas is no longer cooperating with the investigation.

Special Master David R. Cohen says in a report obtained by KCUR Radio that 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 seeks.

A message on Monday seeking comment from the U.S. Attorney’s office was not immediately returned.

The decision may heighten suspicions that the office is concealing information about tapings from criminal defense lawyers, many of whom have filed motions to dismiss cases on the grounds that clients’ constitutional rights were violated.