Fulton County sheriff's deputies plotted to kill Brian Nichols while he was in the Fulton County jail, his attorneys said in a court filing Wednesday.

"Deputies charged with Mr. Nichols' protection and safekeeping were in fact scheming and/or devising scenarios to enable them to justify killing him," defense lawyers alleged in court papers. "Not only were these deputies attempting to bait Mr. Nichols so they could use lethal force against him, these deputies were doing so in a manner that placed the lives of other deputies at grave risk."

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Sheriff's spokeswoman Nikita Hightower said she couldn't comment because the judge has imposed a gag order in the Nichols case. "I can't say whether it is true or not," she said.

The court filing cites an anonymous source whom defense lawyers say told them about the plot and feared retribution from the sheriff's office.

The source said members of the jails Special Operations Response Team tried to put Nichols in an unsecure situation in which he would attack one of them and could be killed in response. The court filing said this included having a single deputy being alone with Nichols when he was unrestrained — a violation of jail policy.

"Deputy X told Deputy A that the reason he had Deputy A remove the restraints from Mr. Nichols while Deputy A and Nichols were alone was because if he (Nichols) 'decided to make a move, we were going to kill him,'" the filing said.

Two deputies reported the plot to their superiors but no action was taken against any of the alleged plotters, the filing said.

Previously, the only public allegations of misconduct by the sheriff's office involved a deputy who was accused of smuggling contraband, including a cellphone, to Nichols. Authorities suspect Nichols used the cellphone to plot an escape, but so far no charges have been filed.

Nichols is charged with murdering four people: a deputy, a judge and a court reporter in the courthouse and a federal agent while he was on the run in 2005.

Defense lawyers acknowledged they learned of the possible threat against Nichols shortly after he was moved to the DeKalb County Jail.

They contended they were bringing it up now because prosecutors may bring evidence that Nichols tried to escape and still posed a danger while jurors are deciding whether to impose the death penalty.

According to the court filing, District Attorney Paul Howard told defense lawyers that Nichols was moved to DeKalb "to protect him from the danger of others within the jail who might harm him."

U.S. District Judge Marvin Shoob, however, has said he ordered Nichols moved at Howard's request because Nichols was plotting an escape.

On Wednesday, in another court filing, Nichols' lawyers also asked the judge to prevent jurors from hearing any evidence of the escape plan.

Jury selection in the Nichols case will move Thursday to Atlanta Municipal Court, where it will stay until the case is complete. Until now, prospective jurors were reporting to the Fulton County Courthouse, the scene of three of the four killings.

Fulton County struck a deal with Atlanta to take over a floor at the city's courthouse in exchange for a $376,000 debt for court services.

Staff writer Rhonda Cook contributed to this report.