Karen Read’s defense called its first witness on Friday, marking a new phase in her retrial in the killing of John O’Keefe, her off-duty Boston police officer boyfriend whose body was found buried in the snow outside a home in Canton,

Karen Read's defense team challenges murder allegations in the death of Boston Police Officer John O'Keefe, as the prosecution rests its case with key testimony.

Prosecutors’ crash reconstruction expert testified about the sudden acceleration Read’s SUV made and what injuries are consistent with a car crash.