The prosecution in Karen Read’s trial aimed to solidify its story regarding the death of Boston Police Officer John O’Keefe by using data from a crash expert that placed Read at the location during O’Keefe’s last moments on the morning he died.

Read, aged 45, is charged with striking her boyfriend, 46-year-old O’Keefe, with her Lexus SUV in a drunken fury in the early hours of Jan. 29, 2022, before abandoning him to freeze to death in the yard of a fellow officer’s residence in Canton, Massachusetts.

On Tuesday, special prosecutor Hank Brennan called what is likely the state’s final witness. Dr. Judson Welcher, an accident reconstructionist and biomechanical engineer at Aperture LLC, testified that the black box data in Read’s vehicle did not record a collision on the morning of O’Keefe’s death. He clarified that this absence of data is expected, as the system only detects car-to-car collisions, not those involving 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.