Testimony is continuing in the murder trial of Karen Read, who is accused of backing her SUV into her Boston police officer boyfriend, John O’Keefe, and leaving him for dead. On Friday, Prosecutor Adam Lally called Andre Porto and Ash Vallier, analysts at the State Police crime lab, to the stand.

DEDHAM, Mass. — Friday marks Day 17 of witness testimony in Karen Read’s murder retrial. Read, 45, is accused of striking John O’Keefe, her Boston police officer boyfriend, with her SUV and leaving him to die alone in a blizzard outside of a house party in Canton at the home of fellow officer Brian Albert following a night of drinking.