Thirty-four years after Annie Mae Aquash’s frozen body was found on a South Dakota Indian reservation, the federal case against a man accused of assisting in her killing has been further delayed due to the discovery of a box of evidence in the basement of the Denver Police Department.

The attorney for Richard Marshall says the collection of files and recordings labeled “Aquash” – whose existence police revealed to prosecutors in late January – are new to the case.

Marshall is charged with murder and aiding and abetting in the death of Aquash, who moved to the Pine Ridge Reservation from Nova Scotia in 1973 during the American Indian Movement’s 71-day occupation of Wounded Knee. Prosecutors say AIM leaders suspected she was an FBI informant and ordered her killing in 1975. Prosecutors have said she was not working for the government.

Marshall’s trial had been scheduled to begin Tuesday in Rapid City, but defense attorney Dana Hanna asked for more time to review the new information. On Thursday U.S. District Judge Lawrence Piersol ordered from the bench that the trial be moved to April 13.

“I have discussed the need for a continuance with my client Richard Marshall and he agrees with my advice and opinion that a continuance is necessary to confront his accusers and to present evidence in his defense effectively,” Hanna wrote.

Neither Hanna nor federal prosecutors would comment about the case.

State prosecutors have said John Graham and two other AIM members – Arlo Looking Cloud and Theda Clarke – abducted Aquash in Denver and drove her to Rapid City, where she was held against her will and questioned about whether she was an informant. Prosecutors allege Graham raped Aquash and later fatally shot her.

Marshall’s alleged role in the murder is not clear in court documents.

Graham has pleaded not guilty in state court to one count of felony murder in relation to kidnapping, one count of felony murder in relation to rape and one count of premeditated murder.

Looking Cloud, a key witness in Marshall’s case, was convicted as an accomplice in 2004 and is serving a life sentence. Clarke, also expected to testify, has not been charged. She’s in her 80s and lives in a nursing home in western Nebraska.

Denver police have acknowledged some records from the case were destroyed in 2001. In December, Piersol ordered prosecutors to contact Denver authorities to determine what evidence was gathered and what evidence was destroyed.

A Jan. 21 letter from Denver Police Commander of Major Crimes Jonathyn Priest to Robert Mandel, assistant U.S. attorney in Rapid City, revealed the Jan. 11 discovery of the “Aquash” box and outlined some of the missing evidence, court documents show. The government delivered about 800 pages of documents and about 20 tape recordings Wednesday, Hanna said.

“Some of the documents I had never seen before yesterday and some of the tapes I have never heard before yesterday,” Hanna wrote Thursday.

One of those recordings was an interview between Denver investigator Abe Alonzo and two government witnesses, Hanna said. One of those witnesses is expected to testify against Marshall.

A court report from a hearing held late Thursday shows that Piersol was worried about going to trial without knowing what was in the box.

Norman Zigrossi, the Rapid City FBI director at the time of Aquash’s killing, said he doesn’t think the delay will hurt the government’s case against Marshall.

“We’ve been delayed so long, it really doesn’t mean anything,” Zigrossi said Friday. “The evidence we have won’t change.”