District Attorney Paul Howard lashed back at Brian Nichols and his defense team Monday for using "unfounded allegations" to "smear" a former prosecutor to try to derail the death penalty in Nichols' upcoming murder trial.

Howard is asking Superior Court Judge Jim Bodiford to stop defense lawyers from using unproven charges to attack former prosecutor Gayle Abramson.

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The former prosecutor has not been convicted of a crime and the law requires convictions — not allegations — before a crime can be used to challenge a witness' credibility, Senior Assistant District Attorney Christopher Quinn said in the 13- page filing.

The prosecutor noted an Georgia appellate court had ruled that a police officer couldn't be questioned about his use of illegal drugs in a case that was unrelated to his drug use.

"Impeachment of a witness is limited to general character for truthfulness and by certified copy of prior convictions," Quinn wrote. "Instances of misconduct may not be used to impeach a witness' character or veracity unless the conduct has resulted in the conviction of a crime involving moral turpitude."

Nichols' attorneys have claimed Abramson's "gross misconduct" while on a trip to California in 2004 raised questions about her judgment when she was prosecuting Nichols for rape in 2005. Nichols contends Abramson overlooked factors, including evidence of his impaired mental health, and sought a sentence of life in prison when the other factors suggested he didn't deserve the maximum penalty on charges of kidnapping and raping his former girlfriend.

Nichols escaped from the courthouse on March 11, 2005 while on trial for rape and is accused of murdering four people including the judge and a court reporter. He has entered a mental-health defense.

Last week, Nichols accused Howard of covering up the misconduct by Abramson — now a key witness in the murder case — and asked Bodiford to bar the death penalty and certain evidence and sanction the Fulton County district attorney.

The defense lawyers never specified the misconduct in the court filing.

Howard became aware of the issue because a man Abramson visited in California was a friend of Scott Davis, who was later convicted of murdering a Buckhead millionaire.

Davis contended Abramson had gone to California to gather evidence against him. Abramson denied any role in an undercover operation and insisted her friendship with Davis' friend was coincidental.

She released a statement last week in which she said she had been drugged while on the trip to Palo Alto, Calif., and sexually assaulted. She said she had a memory of awakening and seeing illicit drugs in the room.

Abramson did not report the incident to police. The Atlanta Journal-Constitution does not routinely identify sexual assault victims but Abramson went public in her statement to the AJC.

In Monday's filing, Quinn said Abramson had no professional obligation to offer Nichols a shorter sentence on the rape charges. Quinn accused the defense team, including Henderson Hill, renowned litigator from North Carolina, Robert McGlasson of Decatur and Josh Moore, of the Georgia Public Defender Group, of engaging in a "smear campaign."