Warning: Story contains graphic details.

Luka Rocco Magnotta's first-degree murder trial has heard that a cryptic fax from a Toronto lawyer led homicide detectives to his victim's head.

Magnotta is charged with first-degree murder in Jun Lin's slaying and dismemberment in May, 2012.

Story continues below advertisement

Montreal homicide detective Antonio Paradiso testified Wednesday that he was working on Canada Day in 2012 when a fax told him where to go in a sprawling Montreal park to find what he was looking for.

Paradiso said the letter from Toronto lawyer Raphael J. Feldstein contained directions and suggested that authorities would find what they were looking for if they followed the directions within.

Police at that time were still looking for Lin's head after finding the rest of his body parts a month earlier.

Paradiso tried unsuccessfully to reach Feldstein to get a more specific location.

Story continues below advertisement

"At this point, we were still looking for a body part, the head," he said.

He and his partner, with the help of a canine unit, found it later that day in an overgrown area near a pond.

Paradiso described his role in the case as a "supporting investigator" whose tasks included identifying surveillance video at various locations. He also met with friends and parents of the victim.

The investigator told the jurors Wednesday that homicide detectives initially thought that Magnotta was the victim before they quickly realized he was the suspect.

Story continues below advertisement

Paradiso said he was dispatched to the Montreal airport on June 1, 2012, as Magnotta had booked a return flight from Paris to arrive on that day. But the native of Scarborough, Ont., was not on the plane.

Paradiso was one of the team that eventually flew to Berlin, where Magnotta was arrested on June 4.

Six police officers, including an inspector, were on the flight that brought Magnotta back to Canada. There was also a psychiatrist.

In the kitchen area of the plane, Paradiso read Magnotta his rights and showed him the arrest warrants after German police had handed him over.

Story continues below advertisement

Magnotta said he had already spoken to his lawyer and that he was going to maintain his right to silence, Paradiso testified.

Paradiso was tasked with minding the shackled Magnotta on the flight and even cut up the accused's food for him as he was handcuffed and shackled.

Magnotta didn't say much, ate, used the toilet twice and slept through much of the flight.

The jury also heard later from forensic toxicologist Catherine Lavallee, who testified that the sleep drug Temazepam as well as Benadryl, an over-the-counter allergy medication, were found in Lin's system.

Temazepam, sold under the commercial name Restoril, comes in pill form and is typically only available with a prescription in Canada. It is often used for people who have trouble sleeping.

Story continues below advertisement

But Lavallee noted almost any medication can now be purchased on the Internet.

The court had initially heard about the existence of the drugs last week from forensic pathologist Yann Daze.

Lavallee said Temazepam was also found in a wine bottle discarded in the trash, but she couldn't say how much there had been because the bottle was empty.

The drugs taken together can result in dizziness, confusion, drowsiness, loss of motor skills and even amnesia. The combination of the two and alcohol could render a person incapacitated, she said.

Under cross-examination, Lavallee said she couldn't determine whether Lin voluntarily ingested the drugs.

Story continues below advertisement

The exact amount consumed was impossible to pinpoint because of the state of the body and because she didn't receive any urine or blood samples, which could have made such a calculation possible.

The level of drugs found in the system would have been higher right after death compared with days later when she examined the remains.

"The quantities could have been different at the time of death," Lavallee said.

Earlier on Wednesday, the jury heard that most of the attempts at cleaning his blood-spattered apartment were poorly done.

Forensic biologist Jacinthe Prevost examined the apartment and other exhibits gathered at the crime scene. She had initially suggested the apartment appeared to have been cleaned, but admitted under cross-examination that it was not done well.

Prevost testified she analyzed sperm stains found around the bachelor pad and on discarded clothing in trash behind the building without finding any with links to Lin.

Magnotta, 32, has admitted the physical acts of which he is accused but has pleaded not guilty by way of mental disorder.

He faces four other charges: 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.