On June 23, 2020, 33-year-old Carlis-Brandon LeSean Brabson was found shot to death in the parking lot of the Sable Cove Apartment complex in Aurora, Colorado. Initial reports described the death as suspicious; the Arapahoe County Coroner later determined Brabson had been shot in the back of the head and no firearm was recovered at the scene. Neighbors reported hearing a single gunshot that night.

Security camera footage from the complex showed Brabson earlier that evening attempting to contact his ex-girlfriend, against whom he had a restraining order, claiming he had left his phone in her apartment. Detectives say only Costello and Brabson are visible on the footage at the time of the shooting. Costello was arrested in possession of a gun linked to Brabson’s death, charged with first-degree murder, and later convicted and sentenced to life without parole. Brabson was a father of three daughters; his family described the lasting loss they continue to feel.