Monique Charles was sitting behind the wheel of a Jeep Wrangler and saying goodbye to her mother in Silver Spring when she was ambushed by an assailant who fired multiple rounds at her.

Charles, 47, was about to head home to Brooklyn, New York, on Sunday morning, when her ex-boyfriend, Earl Walker, 47, of Derwood, began shooting. The charging document and warrant, which provided details of the killing and charged Walker with first-degree murder, was obtained by The Banner on Wednesday.

Charles’ mother witnessed the killing, according to the warrant. She told Montgomery County Police that Walker and Charles broke up three years ago. She also said that he had stalked, and had a history of domestic violence against, her daughter.

She was “standing at the passenger-side door saying her goodbyes,” the warrant says. Charles’ mother “heard numerous gunshots” and saw her daughter “slump over into the front passenger seat.”

Charles’ mother had known Walker for more than 20 years and immediately recognized him, the charging document says. She also told police that Walker drove away in a maroon car, which investigators later identified as a Chrysler sedan. Charles’ mother was also able to confirm Walker’s identity to the police with a picture.

Video footage from neighbors’ security cameras showed Walker’s car parked on Imperial Drive at 8:10 a.m. on Sunday. Eight minutes later, the “maroon sedan pulls up next to the victim’s parked vehicle at which time numerous shots can be heard,” according to the police’s narrative.

Charles died next to the parked Wrangler, police said.

Earlier this week, police said they found Walker near his residence in Derwood and saw him driving away. Officers pursued Walker, whose vehicle rolled over after crashing near Route 108 and Rocky Road.

He sustained minor injuries that were not considered life-threatening. A gun was found in Walker’s car, police said.

Walker is facing other charges, including first-degree assault and second-degree assault, according to the charging document. A district court judge on Wednesday held him without bond, according to a spokesperson for county prosecutors.

It was not immediately clear on Wednesday afternoon if Walker had retained an attorney. Neither Charles’ or Walker’s family could be reached for comment.