The long-running case over the 2017 killing of off-duty D.C. police Sgt. Tony Anthony Mason Jr. returned to a Baltimore courtroom Tuesday, as jury selection got underway in the retrial of defendant Dion Thompson. Thompson pleaded not guilty as the court began calling potential jurors, reopening a case that had previously gone through a full trial without a verdict.
Jury selection underway
According to Baltimore Witness, jury selection began Tuesday in the retrial of Thompson, 27, who was in the room as a new panel was assembled at the Baltimore City Circuit Court. The outlet reports that Thompson entered not-guilty pleas before the selection process began.
Charges and cold-case push
Baltimore City State’s Attorney Ivan Bates announced charges in April 2024 and said the case would be the first handled by the office’s new Cold Case Unit, according to a press release from The State’s Attorney's Office. Prosecutors and local media say investigators used a tip in early 2023 to revive the stalled investigation and prepare charging documents, and CBS News previously detailed the arrest and allegations laid out in those papers.
The 2017 shooting
The victim, Sgt. Mason, 40, was shot and killed while sitting in a parked car on the 2800 block of Elgin Avenue in West Baltimore on Nov. 4, 2017, and the woman with him was wounded, The Washington Post reported. Mason was off duty at the time and a 17-year veteran of the Metropolitan Police Department.
Retrial follows mistrial and courtroom tensions
The new proceedings follow a weeklong jury trial in March 2025 that ended in a mistrial after jurors could not reach a unanimous decision, Baltimore Witness reports. The same outlet notes that arguments between prosecutors and defense attorneys during that earlier trial grew so heated that the presiding judge ordered the courtroom gallery cleared. The retrial is scheduled to resume Wednesday, with jury selection expected to continue before Baltimore City Circuit Court Judge Cynthia H. Jones.
What to expect next
If a jury is ultimately seated, attorneys will move into opening statements, evidence, and witness testimony, a phase that could stretch over days or weeks depending on witness availability and the court’s crowded docket. The drawn-out jury selection alone is likely to test both sides’ strategies for screening out bias in a case that has drawn attention in Baltimore and nearby Washington.
Legal notes
Maryland law generally permits the state to retry a defendant after a hung jury, although courts have recognized limits when a mistrial stems from prosecutorial recklessness. Judges apply a “manifest necessity” standard when deciding whether another trial is allowed, The Daily Record reported. The outlet notes that the state’s appellate courts have left open narrow circumstances in which a retrial could still be barred.
