The man authorities say hijacked a bus in Atlanta on Tuesday and shot a passenger dead has 19 prior arrests and a history of mental illness, FOX 5 Atlanta reports. 

Joseph Grier, 39, was arrested after holding a bus driver at gunpoint and holding the remaining 17 commuters hostage as he led police on a wild chase through Atlanta, DeKalb County and Gwinnett County.

Grier's father's partner, Vivian Powell, told FOX 5 that Grier had been diagnosed with bipolar disorder and schizophrenia. She said he has been struggling with mental illness for the 16 years she has known him, and he has been receiving medical treatment.

"My God, Lord have mercy, it's Joseph," she told the local TV station about when she learned what was happening. "I feel bad. My heart goes out to the other family, but it could have been so much worse. There were 17 people on that bus. Suppose all of them got shot?" 

ATLANTA BUS HIJACKING SUSPECT WAS INTERVIEWED BY REPORTERS AS WITNESS AFTER FOOD COURT SHOOTING

Joseph Grier pre-bus hijacking

In this image taken from video, Joseph Grier speaks with reporters about a shooting in the food court of the Peachtree Center development in downtown Atlanta on Tuesday, June 11, 2024. (AP Photo)

She describes him as "soft," "calm" with a "loving demeanor" when he is well-rested and taking his medication. However, that was not the case recently, she said, as he had lost his job, stopped taking his medication and had not been getting much sleep. 

"I’m bipolar, I’m gonna tell you all that, and I’m off my medication for like two weeks," Grier said Tuesday afternoon, appearing agitated and adding that he felt like a "snitch" for describing what he had seen at an unrelated downtown Atlanta food court shooting prior to the bus hijacking.

Not long after being interviewed, Grier allegedly hijacked a commuter bus, ordering the driver at gunpoint to hit the gas and panicking the passengers. By the time the bus rolled to a stop some 40 minutes later, authorities said, Grier had fatally shot one passenger and led officers on a dramatic chase through multiple jurisdictions.

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Hijacked atlanta bus with investigators

A Gwinnett County, Georgia, commuter bus sits on the road where it was stopped in Smoke Rise, Georgia, on Tuesday, June 11, 2024. Atlanta police say the transit bus fled from officers responding to a dispute on board, leading them on a wild and lengthy chase into a neighboring county before it was stopped. (AP Photo/Ben Gray)

Police said Grier had boarded a bus bound for a suburban Gwinnett County park-and-ride lot 26 miles away. Atlanta Police Department Chief Darin Schierbaum told reporters that investigators believe Grier did not have a gun when he boarded the bus.

At some point, he got into a fight with passenger Ernest Byrd Jr. When the 58-year-old Byrd pulled a gun, according to the Georgia Bureau of Investigation, Grier took the gun and fatally shot Byrd. Grier then threatened to shoot the driver if he stopped.

"He said he was ready to die, but he wanted the people of the bus to be safe," Marie Jose Antoine, the wife of the bus driver, told FOX 5. 

ATLANTA HIJACKER WHO LED POLICE ON WILD CHASE IN CROWDED PUBLIC BUS IDENTIFIED

Ernest Byrd

This undated photo provided by Bryanna Byrd shows Ernest Byrd. Byrd was fatally shot by Joseph Grier who hijacked a commuter bus, ordering the driver at gunpoint to hit the gas and panicking the passengers on Tuesday, June 11, 2024, in Atlanta. (Bryanna Byrd via AP)

As for his criminal history, Grier was last released from prison a decade ago after serving time for a 2011 aggravated assault, FOX 5 learned from the Georgia Department of Corrections. Some of his criminal past involved the use of a handgun and knife. 

Grier is charged with one count of murder, one count of hijacking a motor vehicle, 13 counts of aggravated assault, 14 counts of kidnapping, one count of possession of a firearm by a convicted felon and one count of possession of a firearm or knife during the commission of a crime.

CROWDED PUBLIC BUS HIJACKED, TAKEN ON WILD HIGH-SPEED CHASE DOWN ATLANTA FREEWAY; 1 KILLED

Joseph Grier

Joseph Grier, 39. (Fulton County Sheriff's Office)

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Fulton County District Attorney Fani Willis, best known for her prosecutions of former President Trump and rapper Young Thug, asked state officials on Wednesday to appoint a special prosecutor in Grier's case. 

Grier waived his first court appearance Wednesday morning, FOX 5 reports. Online records did not list an attorney who could comment on his charges.

FOX News' Bradford Betz and The Associated Press contributed to this report.