The prosecution in Karen Read’s trial looked to cement its narrative surrounding the death of Boston Police Officer John O’Keefe by turning to a crash expert’s data placing Read at the crime scene during O’Keefe’s final movements on the morning of his death. 

Read, 45, is accused of hitting her boyfriend, 46-year-old O’Keefe, with her Lexus SUV in a drunken rage in the early morning hours of Jan. 29, 2022, before leaving him to freeze to death in the front yard of a fellow officer’s home in Canton, Massachusetts.

On Tuesday, special prosecutor Hank Brennan called the state’s likely final witness to the stand. Dr. Judson Welcher, an accident reconstructionist and biomechanical engineer with Aperture LLC, testified that the black box data within Read’s vehicle did not register a collision on the morning of O’Keefe’s death, but he insisted the lack of data is expected because the system only registers car-to-car crashes, not pedestrians.

“Based on the totality of the evidence, DNA, everything I’ve talked about, that is consistent with that happening,” Welcher said. “With a reasonable degree of scientific certainty, that is what happened.”

Welcher’s testimony served to further solidify the data findings by Burgess and Cellebrite expert Ian Whiffin, who previously took the stand as witnesses for the prosecution in Read’s case. 

The prosecution is expected to rest its case this week after an entire day of Welcher’s direct examination. If convicted of the top charge, second-degree murder, Read faces the possibility of life in prison.

“So far, without cross-examination, the defense is having a bad day,” Lu said.