A man who plowed into a crowd of Harlem pedestrians while fleeing police, killing a nun, has pleaded guilty to murder.

On the morning of June 22, 2010, police investigating a string of gunpoint robberies stopped a minivan occupied by Dyson Williams and William Robbins near W. 142nd Street and Adam Clayton Powell Boulevard, according to a press release from the office of Manhattan District Attorney Cy Vance. As officers questioned Robbins outside the vehicle, Williams, who was in the passenger seat, got behind the wheel and drove away.

Police reportedly pursued with lights and sirens. At W. 122nd Street and Lenox Avenue, Williams collided with another vehicle and careened into a group of people.

Four bystanders were injured. Sister Mary Celine Graham, 83, was killed.

Williams was charged with murder, along with a host of other charges related to the crash and the robberies. Today in state Supreme Court, he pleaded guilty to second degree murder, robbery and assault. Williams, 22, faces 18 years to life in prison. His sentencing is scheduled for May 30.

"Murder was not committed with a gun or a knife in this case, but a car," said Vance. "Before the deadly crash, the defendants in this case had embarked on terrifying gunpoint robbery spree in Harlem. Dyson showed an utter disregard for human life and his actions had tragic and deadly consequences."

Robbins was also charged with murder. Since he was not in the vehicle at the time of the crash, experts said the case against Robbins will test the boundaries of the state's felony murder statute. Robbins is next due in court on May 14, according to an online court database.

In the aftermath of the crash, NYPD Commissioner Ray Kelly said no departmental rules were broken. Kelly characterized the chase that preceded the collision as "appropriate police tactics."

The crash that killed Sister Mary Celine was one of a series of NYPD chases around that time that resulted in injury and death. Six months earlier, Karen Schmeer was fatally struck by men suspected of taking over-the-counter allergy medicine from a CVS pharmacy on the Upper West Side. In August 2009, restaurant worker and father of three Pablo Pasares was run over in Long Island City by a man after an alleged drug buy. According to witnesses, a suspected car thief was fleeing police when he hit and killed 38-year-old Greenpoint mother Violetta Kryzak in April 2009. In February 2009, a video camera captured an apparent Staten Island chase that led to the death of a couple with young sons. In June 2009, nine people, including five pedestrians, were injured when officers responding to a call in a marked NYPD squad car collided with another car and ended up on an East Village sidewalk.