The Karen Read trial is now in the hands of the defense, which called its first witness Friday. The prosecution rested its case in the high-profile Massachusetts murder trial on Thursday after weeks of testimony from 38 witnesses.

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.

Karen Read's defense opens their case after more than a month of testimony from prosecution witnesses. The Massachusetts woman is charged with murder in the death of her boyfriend John O'Keefe, a Boston police officer.