Brian Nichols' defense attorneys filed a deposition Friday that they say shows District Attorney Paul Howard may have perjured himself when he testified about why he didn't investigate a report that one of his top prosecutors was using illegal drugs.

Howard says he didn't investigate because he didn't believe it was true.

PHOTOS • A look at the case 2005-present • Penalty phase | Verdict • Weeks in court: 1 | 2 | 3 | 4 | 5 | 6 | 7 • Interactive graphic: The 2005 shootings • Video: Nichols' confession MORE STORIES 4 years after attacks, courthouse lacks security plan  Gwinnett won't prosecute Nichols for kidnapping  Feds won't seek death penalty for Nichols  In prison, cellphone is coveted contraband  Police reveal little about Nichols manhunt errors  Nichols trial holdouts: 'Show me something'  Nichols says he was at war with U.S. government in taped confession AJC's full trial coverage RELATED LINKS Atlanta news Georgia and metro news

Nichols' attorneys want Howard sanctioned by the court for prosecutorial misconduct and say his office barred from seeking the death penalty for Nichols. Jury selection for Nichols' trial began Thursday and is expected to resume Monday.

The allegations of drug use concern Assistant District Attorney Gayle Abramson, who was prosecuting Nichols on rape charges when he escaped from his holding cell at the Fulton County Courthouse and killed four people, including a judge, on March 11, 2005.

Nichols has admitted to the killings but has pleaded not guilty because he says he was insane at the time.

Nichols' lead attorney Henderson Hill deposed Howard in March 2007 and contends Howard has been hiding the evidence that Abramson used drugs in August 2004.

The defense team filed court papers on Friday to bolster an earlier request for Superior Court Judge James Bodiford to require Howard's office to turn over internal documents that the defense wants to examine for evidence of prosecutorial misconduct in the Nichols case.

The Friday filing also asks the court to require Howard and his staff to submit to depositions regarding the office's handling of the Nichols case and regarding Howard's handling of the Abramson allegations. The last deposition of Howard had been voluntary and he had refused to answer many of the questions Hill asked.

The transcripts of that deposition show a combative Howard, who contended Hill was only out to smear Abramson with allegations about conduct that even if true would have occurred months before she prosecuted Nichols for rape.

Howard acknowledged hearing of the possible drug use when a wiretap of a suspect in an unrelated murder investigation recorded comments referring to Abramson using cocaine and Ecstasy at a party.

"You're asking about a case that has no connection with Brian Nichols," Howard said to Hill. "I don't want to waste time dealing with something that is irrelevant."

Howard said Abramson came to him after the drug allegations surfaced and denied any wrongdoing. Howard said he didn't think the secretly recorded conversation of a murder suspect and his friends was worthy of belief.

Hill and the defense team suggested that Howard's assertion he never investigated Abramson or told her she might be investigated wasn't credible.

"A review of that 'deposition' makes clear that Mr. Howard's intent was to obstruct and frustrate the fact-finding process," the defense said in its request to investigate for prosecutorial misconduct.

The drug allegations surfaced after the courthouse shootings and shortly before Abramson left Howard's office to take a job in private practice. She has denied knowingly taking any illegal drugs while she was a prosecutor and has said she believes she was slipped an illegal drug at the party, which she said allowed her to be sexually assaulted. In a previous prepared statement, she said she saw illegal drugs at the party when she awoke but has no memory of taking any.

Nichols' attorneys contend Howard is hiding evidence of Abramson's wrongdoing because she is a potential key witness in Nichols' murder case. In the Friday court filing they contended:

"When the elected district attorney has made statements under oath about the possible illegal conduct of a witness in a case his office is prosecuting and it appears there is evidence such statements were false ... it is clearly relevant and discoverable information to be allowed to probe and determine whether in fact the elected attorney did in fact lie under oath and any possible motivation for such false testimony."

Nichols' team also contends Abramson's prosecution in the rape case was irrational because she wouldn't offer Nichols a plea deal of less than 15 years in prison, implying that drugs had affected her abilities as a prosecutor, and that she ignored evidence that Nichols was mentally ill.

Jason Graham, an attorney representing Abramson, said Friday that it appeared that Nichols' attorneys were contending that her handling of the rape prosecution helped make Nichols mentally unstable.

"That's just crazy," Graham said. "There is no way you can connect that many dots. There is just not enough ink in the pen."

A court order bars Howard and the defense lawyers from talking outside of court about any aspect of the Nichols case.

The trial for Nichols is expected to take months.

Nichols was in the Fulton County jail while on trial for rape when he brutally assaulted a guard to escape from his holding cell.

He killed the judge presiding over his case and the court reporter in the courtroom.

Then he killed a deputy sheriff while escaping from the courthouse and later that day killed an off-duty federal agent and stole his truck.