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GULFPORT, Miss. — Two more people have been arrested after a Mississippi police officer was gunned down outside his police station.

Harrison County Sheriff Troy Peterson tells WLOX-TV both men were arrested Wednesday on charges of accessory after the fact in the capital murder case.

Twenty-year-old Dalentez Brice and 21-year-old Joshua Kovach are being held without bond. It wasn’t immediately known whether they have lawyers who could be reached for comment.

Veteran Biloxi police Patrolman Robert McKeithen was shot several times in the back Sunday in the police station parking lot.

Nineteen-year-old Darian Atkinson is accused of killing him.

Atkinson’s 21-year-old brother, Davian Atkinson, is also charged as an accessory after the fact. Authorities say he drove his brother to Wiggins after the killing and let him make phone calls.

According to a sworn statement filed by a sheriff’s investigator, Darian Atkinson walked up behind McKeithen in the police station parking lot and shot him several times in the back.

The newspaper reported that a video from outside the Biloxi police station showed Atkinson running through the parking lot after the shooting.

Atkinson was arrested Monday in Wiggins, about 40 miles (65 kilometers) north of the crime scene. He smiled and hummed as he was led into a courtroom Wednesday at the Harrison County Jail in Gulfport, where he made an initial appearance on the capital murder charge.

Atkinson was wearing a knee-length sleeveless vest that the sheriff said is for inmates considered suicide risks. He told Justice Court Judge Brandon Ladner he doesn’t know if he needs a public defender because he hasn’t been able to call his family.

“I got to get on the phone. … I got to talk to my folks,” said Atkinson, who was in wrist and ankle shackles and wearing a green garment that Harrison County Sheriff Troy Peterson called a “suicide vest.”

This photo provided by the City of Biloxi, Miss., Public Affairs Department shows police officer Robert McKeithen who was killed Sunday night, May, 5, outside the department building in Biloxi. (City of Biloxi, Miss., Public Affairs via AP)

Such garments, also called anti-suicide smocks, are designed to be difficult to tear or otherwise fashion into a noose.

Atkinson’s mother, Pamela Broger, told The Associated Press on Tuesday that her son had been having mental health problems in recent months. She said she had to call police to her home because of him.

“There is some truth to that,” Biloxi Police Chief John Miller told reporters Tuesday after a prayer vigil for McKeithen.

Broger also said officers told her they couldn’t do anything because her son hadn’t hurt anyone.

“That’s probably not what was said exactly,” Miller said. He did not elaborate.

Broger declined to comment again Wednesday.

Ladner scheduled a hearing Friday to decide whether Atkinson needs a court-appointed attorney.

Darian Atkinson is being held without bond. A charge of killing a working law enforcement officer, prosecutor, judge or firefighter means the death penalty is possible.

Atkinson’s 21-year-old brother, Davian Atkinson is charged as an accessory after the fact in the killing of McKeithen and also made an initial court appearance Wednesday. The judge said Davian Atkinson is accused of driving his brother to Wiggins and of letting him make phone calls.

Davian Atkinson said he will hire his own lawyer. His bond is set at $500,000. If convicted, Davian Atkinson could face up to 20 years in prison, Harrison County Prosecutor Herman Cox said.