Luc Leclair also handled a hammer as he suggested witness YannDazé did not have the expertise to determine that some of the wounds on Lin's body could have been caused by the tools police found in the trash outside the accused’s Montreal apartment.
Magnotta, dressed in a grey shirt and wearing dark-rimmed glasses, kept his eyes down for much of the cross-examination, but snapped to attention when Leclair turned on the electric saw and hit the table with the hammer.
Magnotta has pleaded not guilty to five charges, including first-degree murder in the death of 33-year-old Jun Lin, but he has admitted to the physical acts behind the charges.
Leclair has told the court he intends to argue that his client should be found not criminally responsible due to mental illness. The Crown has said it intends to prove the actions were premeditated.
Dazé spent the bulk of his testimony on Thursday detailing the results of the victim's autopsy, performed over five non-consecutive days in June and July 2012.
The pathologist told the jury that Lin was likely killed by a slash to the throat, but the witness was unable to conclude whether injuries found on the victim's head were inflicted before or after his death. The remains were significantly decomposed when they were discovered and sent to the pathologist's lab.
The 13-page autopsy report states the head and face wounds were likely caused by numerous blows from a hammer.
Leclair called those conclusions into question Friday as he asked the pathologist what experience led him to decide a hammer was used to inflict the head wounds.
Dazé responded he has performed more than 1,000 post-mortem exams and he called on all of his experience gained in the laboratory. He repeated what he had stated in his testimony Thursday: one impact from a hammer would not have been enough to cause the wounds he observed on the body.
Leclair later referred to the pathologist’s CV, which states Dazé has done 125 autopsies on homicide victims, with fewer than 10 involving a hammer.
Magnotta’s defence lawyer also returned to previous testimony in which the pathologist said he did not watch the video posted online that depicts elements of the killing.
Dazé said earlier that he didn't want to taint his conclusions and had no interest because he sees enough "disgusting things" at work.
Leclair said the video was the "perfect tool" that would have helped the autopsy. He demanded to know why Dazé had not seen the video, going as far as suggesting it bordered on incompetence.
The witness said it wouldn't have assisted the process, and maintained that his job was to examine the body that was before him, without referring to external evidence that could not be verified.
The trial resumes Tuesday with a new witness.