Commonwealth v. Read — Trial ArchiveAndrew Rentschler
Dr. Andrew Rentschler is a biomechanical engineer and accident reconstructionist employed by ARCCA Inc. who was retained as a defense expert witness in both the first and second Karen Read trials. His testimony centered on whether John O'Keefe's head fracture, arm injuries, and body placement were physically consistent with being struck by the rear tail light of a Lexus LX 570 traveling at the speed alleged by the prosecution. Rentschler conducted physical testing using a Hybrid III anthropomorphic test dummy and analyzed injury patterns, force vectors, and tail light damage to support his conclusion that a vehicle strike did not cause O'Keefe's injuries.
Trial 1 vs Trial 2
Between Trial 1 and Trial 2, the examination of Rentschler expanded significantly in both scope and adversarial intensity. In Trial 1, ADA Lally's cross focused primarily on the materials Rentschler had not reviewed and on post-report evidence such as DNA found on the tail light housing. In Trial 2, the prosecution devoted an entire pretrial voir dire session to his communications with the DOJ and his post-trial socializing with the defense, and ADA Brennan's cross in the substantive proceedings added entirely new lines of attack — the deleted text messages, the documentary appearance, and a detailed challenge to his publication record and reference citations. Rentschler also had more testimony to give in Trial 2, spanning two days of direct examination and presenting new analysis critiquing Dr. Welcher's competing biomechanical testing.