MONTREAL -- The jury in Luka Rocco Magnotta's first-degree murder trial has begun hearing the testimony of the forensic pathologist who performed the autopsy on the remains of Chinese student Jun Lin.

Yann Daze says the task was difficult given the body was dismembered and the autopsy had to be conducted over five non-consecutive days.

Daze testified that police initially found most of the body in advanced decomposition in trash behind Magnotta's Montreal apartment building but that the head, feet and hands were missing.

The pathologist also examined tools found in the trash believed to have been used in the slaying, including a knife, a screwdriver, a hammer, a small electric saw and scissors.

The 32-year-old Magnotta has pleaded not guilty to five charges in Lin's slaying in late May 2012, as well as publishing a so-called murder video online.

Daze says he didn't view the video because he knew it was connected to the case and he didn't want to taint his own findings.

He testified Thursday he didn't have any interest in watching the video in any case.

"Frankly, I see enough disgusting things in my line of work, I didn't need to see any more," he told the jury.

Daze explained that conducting an autopsy over five separate days was difficult because pathologists usually do them over consecutive days and know what they are looking for from the start.

When he began the task on June 1, 2012, Daze said he had the majority of the body. Police had found a torso, cut at the neck, shoulders and thighs in a suitcase, as well as arms and legs in the trash.

Daze said the torso was facing upward and was covered in maggots.

He said he also found a piece of paper underneath the torso but fluids coming from the sectioned body part made the note illegible.

The jury has heard previously that Lin's hands and feet would turn up in Ottawa and Vancouver while the head was recovered a month later at a Montreal park.

Magnotta has admitted to the acts he's accused of in Lin's death, but is arguing he is not criminally responsible by way of mental disorder.

The Crown contends the killing was planned and deliberate and says it plans to prove that.

The charges against Magnotta are first-degree murder; criminally harassing Prime Minister Stephen Harper and other members of Parliament; mailing obscene and indecent material; committing an indignity to a body; and publishing obscene materials.

In earlier testimony Thursday, defence lawyer Luc Leclair continued to challenge the credibility of a German man who housed Magnotta in the days preceding his June 2012 arrest in Berlin.

Leclair focused on Frank Rubert's drinking habits after previously going through the witness's lengthy criminal record.

Under cross-examination, Rubert admitted he'd "blocked out" some of the time he spent with Magnotta as he was drunk for a good part of their four days together.

Rubert testified he met Magnotta on a gay chat site and, while he was disappointed he was older than advertised, they spent those days shopping, dining and going to gay bars.

Rubert said through an interpreter that Magnotta showed up at the Berlin bus station via Paris with no luggage, a few thousand euros and reportedly looking for a fresh start after a breakup.