Three months after Alameda County District Attorney Nancy O'Malley announced that her office was reopening an investigation into former BART police officer Anthony Pirone and his role in the 2009 shooting of Oscar Grant, O'Malley announced that no charges will be filed.

At the urging of Grant's family, who have for years contended that Pirone played a key role in the events of January 1, 2009 that left Oscar Grant fatally shot on the platform of Fruitvale Station, O'Malley's office reinvestigated Pirone — who was seen in video from the night holding Grant down before former BART officer Johannes Mehserle fired the fatal shot. And according to court testimony, it was Pirone who was responsible for pulling Grant and his friends off the train and being generally rough in the treatment of Grant.

But, on further review of the evidence, O'Malley announced Monday that there was not enough to charge Pirone with a crime.

"Following an exhaustive investigation and legal analysis, the District Attorney, while condemning Anthony Pirone’s conduct in the strongest of terms, has concluded that he cannot be charged with murder or any other criminal offense," O'Malley said in a statement.

One piece of evidence that had gotten renewed attention, was video that showed Pirone, responding to being called a profane name, leaning in close to Grant and shouting a racial epithet at him.

A 2009 report cowritten by Oakland City Attorney Jayne Williams contended that Pirone set events in motion that night, and his "overly aggressive and unreasonable actions and conduct in violation of policy and acceptable standards contributed substantially to the escalation of the hostile and volatile atmosphere during the course of the incident."

Previously, Mehserle was found guilty of involuntary manslaughter and sentenced to a mere two years in jail. After time served, Mehserle was a free man as of June 2011.

Grant's mother, Reverend Wanda Johnson, spoke at a press conference Monday, as the East Bay Times reports, saying, "My heart hurts today because for 12 years I’ve been crying out for justice for my son."

Johnson continued, "You think about why I’m standing here. My son laid on the cold concrete with that Officer Pirone’s knee on his neck. My son’s head was smashed against the wall and he was kicked and he was pushed. Pirone still walks around free today."

All previous coverage of the killing of Oscar Grant on SFist.

Top image: Protesters calling for justice for Oscar Grant fourteen days after he was shot, on January 14, 2009. Photo by Justin Sullivan/Getty Images