ATLANTA, Georgia (CNN) -- Brian Nichols was convicted Friday of murdering four people in a shooting rampage that began at a courthouse in Atlanta, Georgia. The jury next must decide whether he should be executed for his crimes.
Jurors returned the verdict to a hushed courtroom a few minutes before 3 p.m. Friday. They deliberated for about 12 hours over two days.
Nichols, 36, stood in silence as the 40-page verdict form was read. He was found guilty of all 54 counts, including murder, kidnapping, robbery and escape in the March 2005 rampage that began at the Fulton County Courthouse.
Jurors will return to court Monday morning for the trial's death penalty phase, said Cobb County Superior Court Judge James Bodiford. Bodiford was brought into the case after a Fulton County judge was disqualified.
Some spectators in the courtroom dabbed their eyes, but all heeded Bodiford's stern warning that any emotional outburst would bring contempt of court charges and up to 20 days in jail.
A judge, a court reporter, a deputy and a federal agent were killed in the shooting rampage.
The crime triggered panic throughout metro Atlanta and Nichols was arrested 26 hours after his escape following the largest manhunt in Georgia history. He was taken into custody in neighboring Gwinnett County, where he held a woman hostage in her apartment.
Nichols confessed to the killings but claimed he was legally insane and gripped by a delusional compulsion that he was a slave rebelling against authority. Jurors rejected defense arguments that he was legally insane or mentally ill at the time.
Nichols was accused of overpowering Fulton County sheriff's deputy Cynthia Hall on March 11, 2005, as he was being led into a courtroom where he was facing a second trial on rape charges.
Officials say he 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.
Nichols also was convicted killing David Wilhelm, a federal customs agent, hours later at Wilhelm's home in the Buckhead section of Atlanta.
He was arrested in suburban Gwinnett County 26 hours after his escape, where authorities say he held a woman hostage in her apartment, following the largest manhunt in Georgia history, one that triggered panic in the Atlanta area.
Prosecutors have said Nichols confessed to the shootings shortly after his arrest. The defense did not dispute whether he was the gunman, focusing instead on his mental state and claiming he suffers from a disorder that "overmastered" his will to refrain from criminal acts.
The jury is made up of five African-American women, two white women, three African-American men, a white man and an Asian-American man, court officials said. Their options were to convict Nichols, find him guilty but mentally ill, acquit him or find him not guilty by reason of insanity.
In the penalty phase, jurors will hear impact statements from the victims' relatives and decide whether to spare Nichols' life.
Nichols' trial has been plagued by delays. In October 2007, Judge Hilton Fuller of DeKalb County, who was appointed to hear the case, 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 recused himself from the case after a New Yorker magazine article written by Jeffrey Toobin, who is also a CNN senior 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 that they intended to use a mental-illness defense, claiming Nichols suffered from a "delusional compulsion" at the time of the slayings.
They said he has been diagnosed with a disorder that involves delusions of persecution, 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."
Ashley Smith, the woman Nichols held hostage, has written a book and spoken publicly about how she kicked her addiction to methamphetamine after the ordeal. During their seven hours together, she has said, she gave Nichols drugs but refused to use them with him -- and has not used them since.
Smith, who has married and is now known as Ashley Smith Robinson, testified at Nichols' trial.