COLD CASE CRACKED: Killer convicted 9 years after DC cop’s murder

The shooting happened in November 2017 on the 2800 block of Elgin Avenue in Baltimore. Sgt. Tony Mason Jr., a DC Metropolitan Police officer, was off duty and sitting in his vehicle when he was shot and killed. A second person in the car survived. For nearly nine years, no one was held accountable.

That changed Thursday.

A Baltimore jury convicted Dion Thompson of first-degree murder in Mason’s death, along with conspiracy and attempted second-degree murder charges for the non-fatal shooting of the second victim. Thompson faces two life sentences plus 33 years when he is sentenced on August 5.

The case was the first prosecution brought by the Baltimore City State’s Attorney’s Office’s newly formed Cold Case Homicide Unit, which was created specifically to pursue investigations that stalled or went unsolved through conventional means. Cold Case Homicide Unit Chief Kurt Bjorklund prosecuted the case.

The conviction came through a joint investigation involving the Baltimore Police Department, the FBI, and the Bureau of Alcohol, Tobacco, Firearms and Explosives. Cold case work, by its nature, is incremental — investigators reviewing old evidence with fresh eyes, pursuing angles that were missed or unavailable the first time around. This case was no different.

“For nearly a decade, Sergeant Mason’s death has weighed heavily on his family, our Department, and the community he served,” said DC Metro Interim Chief of Police Jeffery W. Carroll. “We hope this verdict provides some measure of peace for everyone who continues to feel the weight of his loss.”

State’s Attorney Ivan J. Bates called the prosecution a defining moment for the new unit. “Their perseverance has delivered justice for the Mason family,” he said. “As the inaugural case that launched our office’s Cold Case Homicide Unit, this prosecution holds a special place in our hearts as ministers of justice.”

For the Mason family, the wait is over. For Thompson, sentencing is less than a week away.