NEW YORK (CBSNewYork/AP) — Relatives and supporters of an unarmed black teenager shot to death by a white New York City police officer in front of his grandmother and 6-year-old brother are marching 17 miles to bring attention to their cause.

About 30 people started a daylong walk Thursday from Ramarley Graham‘s Bronx home toward police headquarters in lower Manhattan. They chanted, “Whose streets? Our streets.”

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City Councilman Andy King said someone must be held accountable for Graham’s death.

Graham was 18 when he was shot in the bathroom of his Bronx home by an officer who had barged inside during a drug investigation in February 2012.

Prosecutors have said police first encountered Graham when they spotted him and two other people walking into a Bronx bodega on the afternoon of Feb. 2, and then immediately walking out. The officers, who were conducting a street narcotics investigation, said they saw Graham adjusting his waistband and told fellow officers they believed he had a gun.

Police followed him to his Bronx home. Officer Richard Haste made his way into the home, forced his way into a bathroom and shot Graham once.

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In March, federal prosecutors declined to file civil rights charges against Haste. The officer said he thought Graham was reaching for a gun, but no weapon was ever found. Haste’s lawyer has said there were “never any winners in this case.”

The teen’s mother claims there were over 12 officers involved and she wants all them to be fired.

“These officers murdered a young man who didn’t commit a crime, he didn’t do anything wrong. All he was doing was going home and he’s dead,” Graham’s mother, Constance Malcolm, told 1010 WINS. “They need to be off the force.”

Police department disciplinary proceedings are underway.

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