Karen Read trial crash expert links black box data to O’Keefe’s final moments

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.

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Karen Read is shown during her murder trial at Norfolk Superior Court in Dedham, Mass., on May 27, 2025. (Matt Stone/Boston Herald via AP/Pool)

“Were you surprised that there was no information about a collision in the [black box]?” Brennan asked.

“No,” Welcher said. “[It was] exactly what I expected.” 

Welcher testified that he was able to match Techstream data from Read’s Lexus SUV to the vehicle’s infotainment clock using reports from his colleague, Shanon Burgess, showing the moment Read’s vehicle was turned on. 

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Evidence photos from Dr. Judson Welcher’s investigation are shown during Karen Read’s trial on May 27, 2025. (Pool)

“So we’re going from the running clock to a real-world clock,” Welcher said. “If you take when [the vehicle] was turned on from Burgess’ report, you can see that the Lexus was turned on at 12:12:36 a.m.”

The Techstream clock within Read’s vehicle was 21 to 29 seconds behind O’Keefe’s cellphone clock, requiring investigators to advance the data to match the cellphone, Welcher explained.

“That’s why you need to have an apples-to-apples comparison,” Welcher said. “You need to get them on the same time clock.”

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Dr. Judson Welcher testifies during the Karen Read murder trial on May 27, 2025. (Matt Stone/Boston Herald via AP/Pool)

Approximately 19 minutes after the ignition was turned on, Read’s vehicle registered a second trigger event, according to Welcher. Pointing to revolutions per minute, acceleration and shifting data from the black box, Welcher testified that Read’s vehicle drove forward 34 feet before backing up 53 feet at a 74% throttle, with data indicating the car was traveling at 23 mph by the end of the trigger event.

Welcher pointed to data from O’Keefe’s phone, telling Brennan the rapid acceleration of Read’s vehicle matched with the timestamp of O’Keefe’s final interaction with the device. 

“[The trigger event] matches the window of the cellphone data for O’Keefe,” Welcher said. “That puts [the vehicle] in front of 34 Fairview.” 

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Prosecutor Hank Brennan questions a witness during the Karen Read murder trial on May 27, 2025. (Matt Stone/Boston Herald via AP/Pool)

The data corroboration further solidifies the prosecution’s timeline surrounding what allegedly caused O’Keefe’s death outside the Massachusetts home. 

“At best for the defendant, this witness is moderately damaging,” retired Massachusetts Superior Court Judge Jack Lu told Fox News Digital. “Seventy-four percent acceleration, no brake; Welcher is likable and professional but not over the top, sort of humble.” 

Welcher turned his attention to surveillance footage showing Read pulling out of O’Keefe’s driveway shortly before discovering his lifeless body in the snow, testifying that his investigation concluded the bumper of Read’s vehicle did come in contact with O’Keefe, but the taillight did not. 

“I hate to see any party get hurt, but this was a bad day for Ms. Read,” Lu said. “She [was] driving a very high-end luxury Lexus SUV and pushed the throttle beyond 70% with no braking. That Lexus SUV must have taken off like a SpaceX rocket ship. That is the nature of the beast – a very bad look for Ms. Read.”

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Defense attorney Robert Alessi confers with Superior Court Judge Beverly Cannone as Karen Read, left, looks on at Norfolk Superior Court in Dedham, Mass., on May 27, 2025. (Matt Stone/Boston Herald via AP/Pool)

“So the only evidence of contact is nowhere near the upper taillight,” Welcher said. “I emphasize the word ‘upper taillight’ because it is right in line with the lower taillight, but yet the lower taillight was also not broken.” 

The crash expert testified he performed his own experiment with a vehicle that is the same make and model as Read’s SUV to investigate the possible cause of scratch marks found on O’Keefe’s arm. 

Upon learning he was roughly the same height and weight as O’Keefe, Welcher covered the taillight in paint before reenacting a vehicle strike, with video footage indicating the paint left marks on his arm in the same area as O’Keefe’s injuries. 

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“The location orientation of the laceration on O’Keefe’s right forearm and arm are consistent with the geometry and orientation of the right taillight of [Read’s SUV],” Welcher said. 

Welcher testified he also studied the nature of injuries sustained by assaults, telling Brennan his investigation led him to conclude that O’Keefe was struck by Read’s SUV. 

“Based on all the evidence you considered,” Brennan said, “could you share with the jury what your opinion is, to a reasonable degree of engineering certainty, about whether the defendant’s Lexus struck Mr. O’Keefe on Jan. 29, 2022, around 12:32 a.m.?”

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“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. 

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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.