Canadian serial killer Bruce McArthur was in the middle of another possible murder when he was arrested by police last January, a court has heard.

Gruesome details of the 67-year-old's killings have been revealed in court on the first day of his sentencing.

McArthur pleaded guilty to eight counts of first-degree murder last week.

Monday's evidence was so disturbing that a prosecutor took the unusual step of warning the packed court that it could affect their mental health.

WARNING: This story includes some graphic details some readers may find upsetting

"Ask yourself if you need to be here," Michael Cantlon said.

Pictures from McArthur's computer revealed that he posed many of his dead victims naked apart from a fur coat or hats, the court heard.

At least one had his eyes taped open and others had unlit cigars hanging from their lips.

McArthur shaved some of his victims' heads and beards after strangling them, and kept bags of hair in Ziploc bags at a shed near a Toronto cemetery.

The big break on the case came when McArthur killed Andrew Kinsman last summer.

Kinsman had an entry in his diary marked "Bruce" on 26 June 2017, the day he disappeared.

Image captionClockwise from upper left: Selim Esen, Andrew Kinsman, Majeed Kayhan, Dean Lisowick, Kirushna Kumar Kanagaratnam, Abdulbasir Faizi, Skandaraj Navaratnam, Soroush Mahmudi

Video surveillance footage showed him getting into a car that was traced back to McArthur in autumn of that year.

Over the next several months, police kept McArthur under surveillance and covertly searched his apartment with a warrant.

In court, friends and family of Kinsman expressed rage and sorrow while reading their victim impact statements.

"We searched for Andrew for six months. I knew he was gone, but still we looked." his sister Patricia Kinsman told the court, fighting back tears of anger.

"His life was snuffed out by this man. We don't say his name."

Kinsman's friend Adrian Betts said he was angry with himself, for not seeing McArthur for what he was. McArthur had known Kinsman and Skandaraj Navaratnam for years before he killed them.

"I thought I was a good judge of character but I didn't see the wolf in the fold," Betts said through tears in court.

Final victim

McArthur's arrest was precipitated by concern that he had taken another potential victim back to his apartment.

That individual - a married man identified only as "John" in court - fit the profile of many previous McArthur victims.

He had arrived in Canada five years ago from the Middle East, and his family did not know he was gay, Mr Cantlon told the court.

Texts between John and McArthur reveal the two had met on a gay dating app and had discussed keeping their affair secret.

Last January, John went back to McArthur's apartment.

McArthur told him "he wanted to try something different" and pulled out a pair of handcuffs.

He chained John to his four-poster steel bed frame, and put a black bag over his head.

There were no holes in the bag to see or breathe.

When John tried to remove the bag, McArthur tried to tape his mouth shut.

At that moment police knocked on the door.

Image captionBruce McArthur's bedroom, where police believe he killed many of his victims

During their investigation, police uncovered a USB device containing nine folders, with several of the eight victims' names.

The final folder was named "John".

It contained photos of John that were downloaded the same day McArthur murdered Kinsman.

History with the police

The Crown concluded its evidence on Monday afternoon.

It was revealed that McArthur had three encounters with the police before becoming a suspect in Kinsman's murder.

In 2003, McArthur was convicted of assault after hitting a former sexual partner over the head with a metal pipe. In 2014, after he had already committed three murders, he was granted a record suspension, which means his criminal past would no longer be shown on background checks.

In 2013, McArthur was interviewed as part of the police investigation into the disappearances of Navaratnam, Faizi and Kayhan.

As a long-time friend of Navaratnam, police considered McArthur a witness, not a suspect.

Two weeks after he was interviewed, he bought a new van.

Then in 2016, in the midst of his killing spree, he was interviewed by police for a third time, when he tried to strangle a friend in his van.

McArthur had invited the friend into his van, presumably for casual sex, and asked him to lie in the back on top of a fur coat. The victim noted the van was lined in plastic.

McArthur grabbed his wrist and the victim remembered he had an "angry" look on his face. He then started to strangle him with his hands.

"What do you want from me? Why?" the victim asked before finally escaping.

He called the police, and McArthur was brought in for an interview, but not charged.

Police found his version of events "credible" and McArthur's 2003 arrest did not come up on background searches.

More to come

The next two days will be focused on victim impact statements, before his sentencing on Wednesday.

First-degree murder carries a mandatory life sentence, with no parole for 25 years.

The judge said the only thing he must decide is whether to sentence him to consecutive life sentences, or whether McArthur can serve eight life sentences concurrently.

Either way he will not leave prison before he is 91.