Relatives of Ramarley Graham — the unarmed teen who was fatally shot by a cop after being chased into his mother’s Bronx apartment in 2012 — packed a courtroom for the officer’s administrative trial Tuesday.

NYPD Officer Richard Haste, who faces departmental discipline, was part of a narcotics unit in Wakefield that believed Graham, 18, had a gun because he adjusted his waistband when they approached him in the street, police have said. When cops tried to stop him, the teen sprinted for his mom’s apartment a few blocks away.

Police barged into the home after him with their guns drawn. Haste confronted Graham in a bathroom, where cops said the teen was trying to flush marijuana down a toilet. Officers claimed Graham made a move toward his waistband and that’s when Haste shot him once in front of his brother and grandmother.

No gun was found on Graham or in the house. The teenager’s mother, Constance Malcolm, has demanded justice for the past five years, but prosecutors declined to file criminal charges against the cop.

She has insisted that Haste and other members of the Street Narcotics Enforcement Unit be fired.

Haste could face dismissal as a result of the trial, but the public may never know the outcome because state law bars making it public.

Haste has been on modified duty, stripped of his gun and shield, since the shooting.