The U.S. trial opened on Monday of a man accused of murdering a federal judge in a courtroom and three other people during his escape from custody three years ago.

Brian Nichols, 36, pleaded not guilty by virtue of insanity to a series of charges including murder, kidnapping, robbery, aggravated assault and carjacking, according to local television reports.

Prosecutors at Atlanta municipal court are seeking the death penalty in a case that stems from events that gained Nichols instant notoriety and shocked many Americans.

Nichols is accused of overpowering a security guard at Fulton County Courthouse in Atlanta in March 2005, where he was being tried for rape.

He allegedly took the guard's gun and entered the courtroom where he shot dead Judge Rowland Barnes and a court reporter in the presence of several witnesses.

He is also accused of killing a deputy sheriff outside the court. Prosecutors say in the manhunt that followed, Nichols killed a federal agent, hijacked up to five cars and held a woman hostage in her home north of Atlanta before giving himself up.

The case had stalled over funding for the defense team, leading several Georgia legislators to complain about the slowness of the trial. But a new judge, James Bodiford, was named in February and said he was determined to speed up the trial.