Robert McCarthy

Robert McCarthy testified for the prosecution on Day 35 about recovering and examining explosive devices after the Watertown confrontation. A Massachusetts State Police bomb-squad trooper, he described transporting two pipe devices in a containment vessel to Moon Island and opening them robotically to preserve evidence. He described an elbow-shaped pipe and a straight pipe, both lined with BBs and containing hobby fuses. He interpreted a mark on the straight device's fuse as an apparent attempt at ignition. The court allowed his experience-based explanation of the elbow shape over defense objections.

McCarthy also described clearing the Honda and removing a computer bag for x-ray screening. He did not open the bag and was not aware of dangerous items inside. After robotic removal failed, he pulled a Tupperware container from the Mercedes with a rigging line. Technicians x-rayed it, and another technician removed its intact lid. McCarthy described three taped lengths of hobby fuse through the lid and estimated two to three pounds of powder, while acknowledging that he could not give an exact amount. His account addressed the devices' construction and condition, not the identity of their maker or user.

On cross-examination, McCarthy clarified the limits of his observations upon arrival. Although he believed a bomb had gone off, he had seen smoke through streetlights rather than the explosion itself. He explained that he identified Cypress Street from a map afterward and approached from the Mount Auburn side, bypassing Laurel Street before circling toward Dexter. He could not confirm that marked cruisers blocked the route or account for all nearby vehicle movements. He also confirmed the later containment-vehicle staging point and robot deployment.