Crash expert puts Karen Read’s SUV outside party house during critical window of O’Keefe’s death
Karen Read pleaded not guilty to murder charges in the death of Boston police officer John O’Keefe and is facing a retrial after a jury was unable to reach a verdict last year.
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Dr. Judson Welcher reenacted a Lexus SUV strike in court on Tuesday, May 27. (Aperature LLC)
Crash expert Dr. Judson Welcher presented a detailed reenactment of the alleged three-point turn that prosecutors claim led to the death of Boston Police Officer John O’Keefe.
Utilizing laser scans of the crime scene and vehicles, Welcher created computer models and video simulations to illustrate the maneuver.
He showcased a computer model depicting Read's Lexus SUV in a forward movement followed by a high-throttle reverse, which resulted in a three-point turn. He said that the data captured during this maneuver aligned with the window of O’Keefe’s cell phone activity, placing the vehicle in front of 34 Fairview Road in Canton, Mass. between 12:30:20 and 12:32:12 a.m.
In an additional demonstration, Welcher used a vehicle identical to Read's SUV, with him standing in as O'Keefe. Welcher showed pictures of himself dressed as O'Keefe, noting that he was 4 pounds lighter than the police officer at the time of the alleged incident.
Welcher demonstrated that even at a low speed of 2 mph, the SUV's impact was sufficient to disrupt his balance, causing him to step back. He showed where the taillight would have hit his arm, but said "we don't know how he was struck."
Welcher pointed out that there was no damage to the upper or lower taillights, despite a scuff mark located between them. He noted that the lower taillight, which protrudes further than the upper one, remained intact.
Judge Beverly Cannone has paused proceedings for a 45-minute lunch break following an intensive session of testimony from crash reconstruction expert, Dr. Judson Welcher.
Welcher spent the last 20 minutes meticulously analyzing second-by-second data points to reconstruct a critical three-point turn made by Karen Read’s Lexus SUV near 34 Fairview Road in Canton, Mass. on the night of Jan. 29, 2022.
Utilizing data from the vehicle's Techstream system and cell phone records, Welcher presented a simulation at 12:40 p.m. that illustrated the SUV's movements during the maneuver.
Dr. Judson Welcher, an accident reconstruction expert, testified Tuesday about digital data pulled from Karen Read’s Lexus SUV, aiming to pinpoint the vehicle’s movements on the night of John O’Keefe’s death.
Welcher's testimony put Read in the area of 34 Fairview Road, Canton, Mass. during the critical moments of O'Keefe's looming death.
Welcher explained how data from the infotainment system, GPS, and cell phone records were synchronized to establish a timeline.
“I was provided with data, and a report from Mr. Burgess that indicated the infotainment system was turned on at 12:36,” Welcher said.
The data point became a reference to convert the car’s text stream data, which logs time as a running clock, into timestamps.
“You told us that the text stream data does not have an actual clock and has a running clock like a stopwatch?” asked Special Prosecutor Hank Brennan. “And then you mentioned that after you received information from Mr. Burgess, you could put an actual time onto it. How do you do that?”
With the infotainment system activation fixed at 12:36 a.m., Welcher said he could align a trigger in the data stream to 12:23:38 a.m.
Prosecutors also pointed to GPS data placing Read's Lexus SUV near the Waterfall Bar and Grille and described a three-point turn on Cedar Crest Road, near the scene.
“Additional cell phone data that we had is that we knew there was a three-point turn made when the Lexus passed Fairview on Cedar Crest, pulled into a driveway and made a three-point turn,” Welcher said.
Dr. Judson Welcher, a crash reconstruction expert, testified on Tuesday, May 27. (Aperature LLC)
Dr. Judson Welcher took the stand Tuesday as the state worked to close its case in the murder retrial of Karen Read.
In front of a seated jury, Special Prosecutor Hank Brennan began direct examination of Dr. Welcher, an accident reconstruction expert.
“I take my job as to be a critical analysis of the data. So I wanted to look at the data as objectively as possible and form conclusions based upon the data, trying to remove wherever possible, speculation,” Welcher testified.
“Now, sometimes testimony is the only thing we have, and so we need to rely on it for bits and pieces. But generally my job is to try and look at data and see what the data shows. I have no dog in this fight. I don't, quite frankly, care. What I'm doing is trying to do a good engineering job, looking at the data and drawing sound principles and sound conclusions from the data.”
Welcher listed an exhaustive inventory of physical evidence he used to form his conclusions about the crash scene.
His review used materials from the Canton Police Department , cruiser dashboard cameras, Ring doorbell videos, scene photographs, Verizon and Lexus Connect data, lab toxicology reports, and multiple interviews given by Read to media outlets.
“I have police reports, including the Canton PD incident report and eight other reports,” Welcher testified. “I have the Ring video from Mr. O’Keefe’s residence, cruiser cameras, 140 photographs of vehicles, additional photographs of the scene, surveillance video files from McCarthy’s Shipping, Waterfall Bar, Cellebrite data, Lexus infotainment system data, Verizon GPS records, weather reports, medical records, and two retrograde extrapolation reports.”
In an effort to replicate and analyze conditions relevant to the case, Welcher also purchased the same make and model of SUV that Read was driving, a 2021 Lexus RX350, and conducted his own field testing.
He said that he had presented an early version of his analysis to the prosecution team via PowerPoint on January 30, and that he had visited 34 Fairview Road, the scene where John O’Keefe’s body was discovered.
Dr. Judson Welcher, Biomechanical Engineer and Accident Reconstructionist, testifies during the Karen Read murder trial at Norfolk Superior Court, Tuesday, May 27, 2025, in Dedham, Mass. (Matt Stone/The Boston Herald via AP, Pool)
Nationally known accident reconstruction expert, Dr. Judson Welcher, took the stand on Tuesday morning.
Welcher first faced voir dire, a legal vetting process to assess whether he should be accepted as an expert witness.
The voir dire was conducted by Read’s defense attorney, Robert Alessi, who focused on recent modifications made to Welcher’s PowerPoint presentation, which the state intends to use.
Welcher acknowledged that he had altered the presentation within the past 8 to 10 days, removing a slide and changing wording. The edits related to the Dighton route and vehicle mileage, both crucial components in the prosecution’s theory of the timeline.
Alessi pressed Welcher about who he had spoken with about the content and edits. Welcher testified that he had discussed the PowerPoint with Assistant District Attorneys Hank Brennan, Adam Lally, and Mary Ellen Gray, as well as Lt. Brian Tully, an investigator in the case.
Karen Read arrived in court on Wednesday morning as her second trial for the alleged murder of Boston police officer John O’Keefe resumed after a five-day recess.
Dressed in a dark green suit, she was flanked by her lead defense attorney, Alan Jackson, who is preparing to launch their defense as the prosecution wraps up its case.
Tuesday marked a pivotal moment in the retrial. After 21 days of testimony, the prosecution is expected to call its final witness, an accident reconstruction expert, before resting its case.
Karen Read, who is accused of killing her boyfriend Boston police Officer John O'Keefe, in 2022, during her murder trial at Norfolk Superior Court, Tuesday, May 27, 2025, in Dedham, Mass. (Matt Stone/The Boston Herald via AP, Pool)
After nearly two months of witness testimony, expert analysis, and intense cross-examination, the prosecution in the Karen Read retrial is expected to rest its case this week in Norfolk Superior Court.
Read, who is charged with second-degree murder in the 2022 death of Boston police officer John O’Keefe, has maintained her innocence, claiming she did not hit O’Keefe with her car.
Prosecutors allege she struck O’Keefe with her SUV after a night of drinking and left him to die in the snow outside a friend’s home.
Over the past eight weeks, the prosecution has called more than 30 witnesses, including forensic specialists, law enforcement officers, and civilians present on the night in question.
Key evidence has included plastic taillight fragments said to match Read's damaged Lexus RX350, digital forensic analysis of O'Keefe's phone and location and witness testimony who alleged that Read made incriminating statements after the incident.
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