The U.S. attorney's office announced Tuesday the closure of its investigation into the death of Ramarley Graham.

Officials say there is insufficient evidence to pursue federal civil rights charges against the officer involved in Graham's shooting. 

Prosecutors say that they could not prove beyond a reasonable doubt that the officer willfully deprived Graham of his civil rights. Such charges would not include an accident, mistake, bad judgment or negligence.

Graham's mother tells News 12 she thinks that if there had been a more thorough investigation at the time, prosecutors would have come to a different conclusion. 

NYPD Officer Richard Haste shot Graham in 2012 after a brief foot chase that ended in his home on East 229th Street in Wakefield.

Police say they witnessed the 18-year-old allegedly taking part in a drug deal, which prompted two officers to confront Graham, who fled.

Prosecutors say the officers followed, and Haste drew his weapon and ordered Graham to show his hands. The teen reportedly ran into the bathroom.

Haste says he followed Graham and saw him pull something out of his pants -- something that he believed was a weapon. That's when Haste fatally shot Graham. Police later found a bag of marijuana in the toilet bowl.

Graham's grandmother and 6-year-old brother were also in the home at the time. Family members dispute the police account, claiming Graham was shot in the hallway and fell into the bathroom.

Last month, Graham's family rallied outside the NYPD's 47th Precinct and then the Department of Justice building to mark the fourth anniversary of his death.

Haste was indicted on manslaughter charges in 2013, but the case was dismissed after an error by the Bronx District Attorney's Office.

Patrick Lynch, president of the city's PBA, said that the police union is grateful there won't be any charges against Haste, but added that there were no winners in the case.