The Massachusetts judge presiding over Karen Read's second trial in the death of Boston Police Officer John O'Keefe has barred references to the botched Sandra Birchmore investigation.

There was only a half day of testimony on Friday, with court wrapping up at 12:30 p.m. Medical examiner Dr. Irini Scordi-Bello finished testifying Thursday after several hours on the stand, during which graphic photos from John O'Keefe's autopsy were shown to the jury.

According to our Boston affiliate WCVB, the tail light DNA came from three separate people, including at least one male. The sample was a “strong match” for Boston police officer, John O’Keefe. Bradford explained the hair sample found in the back of the SUV did not give enough DNA to identify it.

Ronnie Estanislao, who was on the deadlocked jury in Karen Read's first trial last year, explains the bitter split in the deliberation room as the panel couldn't agree on her guilt or innocence.

Prosecutors say Karen Read hit John O’Keefe with her SUV and left him for dead. On Thursday, a medical examiner testified about his wounds show.

Testimony from John O'Keefe's niece highlights tensions with Karen Read before his death, as Read faces trial for the Boston officer's murder.