Washington ? Terry Nichols’ attorneys say more than a dozen FBI documents that raise the possibility of additional accomplices in the 1995 Oklahoma City bombing weren’t turned over by state prosecutors or the federal government for Nichols’ murder trial defense.

The documents, which were cited in a recent series of Associated Press stories, include two 1990s teletypes from then-FBI Director Louis Freeh’s office citing possible connections between Timothy McVeigh and a gang of white supremacist bank robbers, the lawyers said.

Nichols, already in federal prison, began trial this month on Oklahoma state murder charges alleging he assisted McVeigh in building the deadly bomb. The judge has said he would dismiss the charges with prejudice — making it very hard for prosecutors to resurrect the case — if Nichols’ lawyers could prove documents that could have aided their defense were withheld.

Under a Supreme Court ruling, prosecutors and the government are obligated to turn over to defense lawyers all materials that could help clear a defendant, such as evidence that points to other suspects or casts doubt on prosecution witnesses.

Nichols’ attorneys agreed to review the materials cited in the AP story and identify which they could not find among the massive files prosecutors and the government provided them. In all, they identified 13 FBI documents and a handful of other materials.

“To our knowledge, we have not received these documents from the state or federal government,” lead Nichols’ attorney Brian Hermanson said Wednesday.

In addition, the lawyers said they did not receive any information from prosecutors concerning the FBI’s unsuccessful efforts to get permission to interview McVeigh in 2001 to resolve lingering questions before his execution.

FBI officials declined comment, citing the trial and an ongoing investigation into issues raised by AP’s stories.

McVeigh was executed in 2001. Nichols, 48, is serving a life prison sentence for the April 19, 1995, bombing of the Alfred P. Murrah Federal Building, which killed 168 people. He was convicted in 1997 on federal charges involving eight federal employees. The state charges, which carry the death penalty, are for the 160 other victims and one victim’s fetus.

Nearly all the documents cited by Nichols’ attorneys involved FBI efforts to link McVeigh to the Aryan Republican Army bank robbery gang.

At least two gang members and one gang member’s ex-girlfriend claimed to have knowledge of the bombing plot, but the FBI dropped the inquiry after the robbers denied their involvement and provided an alibi.

Convicted Oklahoma City bomber Terry Nichols arrives at the courthouse in McAlester, Okla., for his state trial. Nichols' attorneys say more than a dozen FBI documents that raise the possibility of additional accomplices in the 1995 Oklahoma City bombing weren't turned over by state prosecutors or the federal government for Nichols' murder trial defense.