Arrest made in cold case of off-duty DC police sergeant killed

BALTIMORE, Md. ( DC News Now ) — An arrest has been made in the murder of an off-duty DC police officer.

40-year-old Tony Mason Jr. was shot to death on Nov. 4, 2017 in Baltimore. He was a 17-year-veteran and sergeant with the Metropolitan Police Department (MPD), his case went cold and no arrest was initially made.

That changed after a tip was received in early 2023.

Wednesday, the Baltimore City State’s Attorney announced the arrest of 24-year-old Dion Thompson. He’s charged with first degree murder, conspiracy and other related charges for the death of Mason.

“A cold case is still very much fresh in the hearts and minds of the victim’s family. My main job as State’s Attorney is holding offenders accountable, bringing closure for those impacted, and ensuring justice for Baltimore, the victims, and their loved ones,” said State’s Attorney Ivan J. Bates.

According to court documents, Mason was on a date on the night of his murder. He and a woman were parked on the 2800 block of Elgin St. in Baltimore when someone opened fire on their car.

Mason was unarmed and not wearing any clothing that would identify him as a police officer. Both he and the female victim, who was also injured but survived, were not connected to any gang affiliation.

In the statement of charges, officials said a tipster claimed Thompson later confessed to killing Mason.

The document states that Thompson became paranoid after seeing Mason’s car and believed the occupants were either there to “rob him or retaliate against him.” Thompson allegedly alerted two other people and the group pulled up in a car next to Mason. Someone opened fire, killing Mason. Sixteen shell casings were found on the scene.

Documents also stated that Thompson is a known gang leader and drug dealer. He’s currently in federal prison in New Jersey on drug charges.

“For far too long, the details surrounding Sgt. Mason’s tragic death have remained a painful mystery. However, the Baltimore Police Department, the FBI, the ATF and the Baltimore City State’s Attorney’s office never stopped following up on tips and tracking down leads,” said MPD Chief Pamela A. Smith.

Baltimore officials credit a new cold case unit with helping solve the case.

“You might think that you’ve gotten away with murder, the but the advancements in technology and us working together we’re going to make sure we try to and focus on holding you accountable,” said Bates.

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