Robert Aaron Long, 22, is now expected to be transferred to Atlanta where he faces four additional counts of murder and where the district attorney has indicated she will pursue hate crimes and the death penalty.

Dressed in a white button-down shirt with an open collar and dress slacks and sporting a mohawk haircut, Long pleaded guilty in court to the murders of four people at the day spa in Cherokee County, about 64km north of Atlanta.

Long - holding his head up but looking sombre - also affirmed agreement with the state's recommendation of four life sentences without possibility of parole, to be served consecutively, plus 35 years on other charges.

The judge confirmed that sentence.

In his first public comments since the March 16 massacre, Long calmly described how he purchased a firearm and a bottle of bourbon and set out to take his own life before deciding to harm the sex industry to which he had a self-proclaimed addiction.

Having been kicked out of his parent's home and despondent over his "sexual struggles," Long told the court that he went to the spa on that day to "act out, receive sexual favours and hopefully hate myself enough to... end my own life".

The shooting spree, carried out in three spas in the metro Atlanta area, galvanised awareness of a wave of anti-Asian violence in the US.

But Cherokee District Attorney Shannon Wallace said her office's investigation did not turn up any bias based on race or gender in the fatal shootings of Delaina Ashley Yaun, 33; Paul Andre Michels, 54; Xiaojie Yan, 49; and Daoyou Feng, 44.

Wallace said her office "was not able to conclude that it was motivated by bias or race" because the shootings involved men and women of different races and people close to Long had never heard him say anything racist.

Judge Ellen McElyea concurred: "I know as much as it would be easy to identify this crime as a hate crime. You harmed people who were not in that category," she said.

Long told McElyea he had been kicked out of his parent's home two weeks before the shooting for paying for sex at a spa in Fulton County and had stopped taking the antidepressant Zoloft prescribed to him for reasons he could not explain.

His parents found out due to a tracking app on his phone.

Long said his mind "felt blank" after firing the first shot.

Wallace said she had intended to pursue the death penalty but the families of the victims had asked to resolve the case quickly without trial.

She and the judge said the families of the slain agreed to the plea agreement.

Australian Associated Press