Abdirahman Mahmoud looks up at his lawyer, Luke Rioux, during the opening day of his trial at the Cumberland County Courthouse on Sept. 23. (Brianna Soukup/Staff Photographer)A fight on St. John Street last year started with allegations of an unpaid bar tab and ended in a fatal shooting. Now, the man who pulled the trigger is asking a jury to agree he acted in self-defense. Authorities have said Mahmoud shot Tshiyuka outside the New Buja Belle bar just after 1 a.m. on March 2, 2024. During the hearing, Rioux indicated Mahmoud was involved in an incident three years ago that left him with a leg injury.