Authorities in Mississippi on Monday night arrested a man suspected of gunning down a Biloxi police officer in a police station parking lot.

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Authorities identified the slain officer as Robert McKeithen, a 24-year veteran of the Biloxi Police Department.

Officers arrested Darian Atkinson, 19, late Monday night on one count of capital murder in McKeithen's death.

Update 9:30 a.m. EDT May 7: Darian Atkinson's brother, 21-year-old Davian Atkinson, was booked early Tuesday into Harrison County Jail a charge connected to McKeithen's killing, according to news reports and jail records.

Jail records show Davian Atkinson was booked into jail around 1 a.m. Tuesday on one count of accessory after the fact. Gulfport Police Chief Leonard Papania told WLOX that Davian Atkinson is the brother of Darian Atkinson.

Update 10:15 p.m. EDT May 6: The suspect was identified as 19-year-old Darian Tawan Atkinson, according to Gulfport police officials.

Atkinson was taken into custody Monday afternoon and is expected to be charged with capital murder.

Investigators said they have no motive at this time in the ambush and shooting death of  Officer Robert MCKeithen, according to  WLOX-TV.

The investigation is continuing.

Update 1 p.m. EDT May 6: Gulfport police released new video Monday of the man suspected of gunning down McKeithen on Sunday night.

Police asked that anyone who recognizes the man contact authorities.

Update 11:55 a.m. EDT May 6: Biloxi police Chief John Miller called Monday a "very sad day for the city of Biloxi," as authorities continue to investigate McKeithen's death.

Miller remembered McKeithen as “a fine and decent man” and “ great policeman” who previously served in the U.S. Air Force and who planned to retire at the end of the year.

He is survived by his wife, a daughter, two stepsons and a stepdaughter, Miller said.

“He was a wonderful family man,” the chief added. “that’s where he spent all his time, was with his family.”

Miller noted McKeithen and four other officers were awarded the medal of valor after Hurricane Katrina for saving four children with special needs.

“They saved those children who undoubtedly would have perished,” he said.

Authorities continued to search Monday for the person who shot McKeithen.

“The animal that did this is still on the run,” Miller said. “We’re going to do everything within our power to bring him to justice, for Robert and his family, and for the men and women of the Biloxi Police Department and for the citizens of Biloxi.”

Original report: According to WLOX-TV, the Biloxi police officer was in the parking lot of the city's public safety complex about 10:30 p.m. Sunday when a gunman fired multiple shots at him, then fled. The officer, who was on duty at the time, was taken to a nearby hospital and died, authorities said.

Police told WLOX early Monday that the gunman was still at large. Investigators described the suspect as a slim man wearing a red beanie cap, navy shorts and a black T-shirt. He is about 5 feet, 7 inches to 5 feet, 10 inches tall, police said.

Gulfport police are leading the investigation, Biloxi police Chief John Miller told WLOX.

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