ATLANTA, Georgia (CNN) -- The capital murder trial of Atlanta courthouse gunman Brian Nichols will be moved from the scene of the crime, a judge ruled Thursday.
Earlier Thursday, as jury selection began, Nichols pleaded not guilty by reason of insanity to murder and a host of other charges related to a March 2005 shooting spree that began at the courthouse and killed four people.
Superior Court Judge James Bodiford, brought in from nearby Cobb County, said he was "extremely concerned" about continuing with the trial in the same courthouse where a judge, a court stenographer and a bailiff were gunned down March 11, 2005. A fourth person was shot to death later that day.
Bodiford ruled that "fundamental fairness" made it necessary to move the trial to another location in Fulton County within 10 days.
The judge did not say whether he plans to halt jury selection, but stressed the "time sensitive" nature of his order.
Nichols, 36, is charged with 54 counts, including murder, kidnapping, robbery and escape. Prosecutors have said they will seek the death penalty.
Prosecutors have said that Nichols confessed to his shootings shortly after his arrest. The defense does not dispute that he was the gunman, and instead is focusing on his mental state and ability to form the intent to kill. In court papers, the defense claims Nichols suffers from a disorder that "overmastered" his will to refrain from criminal acts.
Nichols is accused of overpowering a Fulton County sheriff's deputy, Cynthia Hall as he was being led into a courtroom ,where he was facing a second trial on rape charges.
He allegedly took Hall's gun from a lockbox and fatally shot three people at the courthouse -- Fulton County Superior Court Judge Rowland Barnes, court reporter Julie Ann Brandau and Fulton County Sheriff's Sgt. Hoyt Teasley, who attempted to apprehend him outside the building. Watch opening of Nichols' trial »
Nichols is also charged with killing David Wilhelm, a federal customs agent, hours later at Wilhelm's home in the Buckhead section of Atlanta.
Nichols was arrested 26 hours after his escape in suburban Gwinnett County, where he had held a woman hostage in her apartment. It was the largest manhunt in Georgia history,
Eighteen people -- 12 jurors and six alternates -- will be chosen as jurors. Attorneys in the case plan to question about 21 jurors daily after the prospects watch a 38-minute video. Because of publicity the case received, a jury pool of hundreds has been assembled, meaning jury selection is likely to last for weeks.
Nichols' trial has been plagued by delays. In October, Judge Hilton Fuller abruptly halted jury selection on what would have been its third day, accepting a defense motion to stop the trial until questions of funding for Nichols' lawyers were resolved.
In January, Fuller removed himself from the case after a New Yorker magazine article written by Jeffrey Toobin, who is also a CNN legal analyst, quoted him as saying the "only defense" open to Nichols was insanity, "because everyone in the world knows he did it."
Also in January, Nichols' defense attorneys said in court filings they intended to use a defense of mental illness, claiming that Nichols suffered from a "delusional compulsion" at the time of the slayings.
The defense says Nichols has been diagnosed with a disorder that involves delusions that he is persecuted, as well as grandiose thinking. Those suffering from such a disorder may function normally and behave rationally, defense attorneys said, but when they encounter circumstances that "touch their delusions, the delusional disorder will preoccupy them and instruct their thinking and actions."
CNN's John Murgatroyd contributed to this story.