A Boston police sergeant will not face criminal charges in an accident last month that killed an 18-year-old Milton High School senior who was struck by his vehicle as she crossed a street near her home, State Police said.

"The State Police investigation into the March 9, 2016 crash that resulted in the death of 18-year-old pedestrian Katelisa Etienne of Milton has determined that criminal charges are not warranted against the driver who struck her,'' State Police spokesman David Procopio wrote in an

e-mail.

Katelisa Etienne. Family handout

The State Police and Norfolk District Attorney Michael Morrissey's office said their investigation found that the driver, off-duty Sergeant Warren Hoppie, 44, of Hyde Park, was not driving at an excessive speed, was not using his cellphone, and was not impaired by drugs or alcohol at the time that his Jeep Wrangler struck Etienne on Brush Hill Road.