The first witness called by Karen Read's defense explained that there were few scenarios where John O'Keefe's phone locked before Read's car accelerated in reverse.

The Karen Read case is back in a Massachusetts courtroom on Monday as the trial enters a fifth week with an 18th day of witness testimony. A forensic analyst for the prosecution is going over the movements of Read's Lexus SUV on the night in question.

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 rested their case after calling a witness responsible for explaining exactly how the supposed collision between Karen Read's SUV and John O'Keefe took place.

Prosecutors rested their case after Dr. Judson Welcher, a crash reconstructionist expert with Aperture LLC, was dismissed from the stand after three days. He most notably testified to the prosecution that damage to Read’s SUV was “consistent with a collision” involving O’Keefe if the vehicle was moving faster than 8 mph.

Aperture, the company Welcher works for, created digital images of O’Keefe’s driveway as part of their analysis of whether Read’s SUV could’ve been cracked when it backed up into O’Keefes Chevrolet the morning he died.

The prosecution in Karen Read’s murder retrial filed a motion on Wednesday asking Judge Beverly Cannone to remove a key piece of evidence from the court record.

Judge Beverly Cannone said that the trial was running "ahead of schedule" before she sent the jury home for the day.