Toronto's record-setting year for homicides was marked by "senseless" violence that has left police struggling to understand its root causes, a top investigator says.

With 11 days left in 2018, Insp. Hank Idsinga, head of Toronto police's homicide unit, reflected on the brutality that claimed the lives of 95 people in the country's largest city.

"What we're seeing this year is very, very senseless murders just happening all over the place in the city," Idsinga said in an interview with CBC Toronto.

There have been 95 homicides in Toronto this year — a figure that Idsinga says has left investigators grasping for motives.

"Sometimes trying to make sense out of any of those [killings], even when you do identify the culprits, and even prosecute and convict them in court, they still don't make any sense," he said.

"So trying to dissect them and trying to determine patterns, is an almost impossible task."

Watch Insp. Hank Idsinga reflect on the surge in killings:

Insp. Hank Idsinga sits down for a year-end interview with CBC Toronto's Dwight Drummond. 1:49

City rocked by high-profile killings

Toronto grabbed worldwide attention in 2018 for a string of high-profile slayings:

The ongoing investigation into the killing of billionaire couple Barry and Honey Sherman.

The arrest of alleged serial killer Bruce McArthur that rocked the city's gay community.

A van attack that left 10 dead and wounded a dozen on bustling Yonge Street.

A shooting rampage on Danforth Avenue in the heart of Toronto's Greektown.

Other brazen shootings in Toronto's public places — the entertainment district, a popular downtown destination and, perhaps most shockingly, a playground where two young sisters were wounded — thrust the issue of gun violence into the spotlight. Gun-related killings account for more than half of all homicides this year.

However, Idsinga said police have seized more guns off the streets than ever before, close to 900 firearms. But the shootings persisted.

"We see it again and again," he told CBC Toronto. "It's frustrating and it's very draining on a lot of the investigators."

Mayor John Tory writes a personal message on a makeshift memorial remembering the victims of a mass shooting along Danforth Avenue on July 22. (Mark Blinch/Canadian Press)

On Nov. 14, after nearly a month without a killing, Toronto hit 89 homicides.

Four days later, a new all-time high was set as the city climbed past its deadly record that stood unbroken for nearly three decades. This forced police and government officials to re-evaluate their approach to gun violence, and sparked calls from the municipal and federal governments for a ban on handguns within city limits.

The last time 89 people were killed in a single year was 1991. Idsinga, a young constable at the time, attributed the rash of violence to "Chinatown and Asian gang" feuds.

"We're not seeing the same thing this year," he said.

Toronto criminologist Maria Jung has pointed out that 1991 is still the peak for both killings and crime in the city because the homicide rate per 100,000 residents is lower now. Mass casualty events like the van attack, which aren't the norm, have also contributed to a higher homicide figure.

Toronto has set a grim homicide record in 2018. (CBC)

'Hundreds of reasons' for surge in violence

Still, that's cold comfort to Idsinga, who said innocent bystanders are being killed indiscriminately and at an alarming rate this year.

"It's very tragic," he said, noting he's shocked by the brazen way guns are being used on the street.

The root cause of the wave in horrific violence is difficult to pinpoint, he told CBC Toronto.

"There's hundreds of reasons that all add up, that contribute to this violence," Idsinga said. He said gang activity, turf wars and retaliation, and guns and drugs all play a role.

Idsinga, a veteran homicide investigator with more than 30 years of experience, led the Bruce McArthur investigation — one of the biggest crime stories in Canadian history. (Evan Mitsui/CBC)

While an uptick in the number of tips police have received has allowed investigators to put out what Idsinga believes are a record number of outstanding warrants in murder cases, he says more work needs to be done.

Of the 712 Toronto homicides over the decade, 248 remain unsolved — that's around 35 per cent, according to police statistics.

Idsinga attributes this to the "large burden" witnesses are faced with when they come forward with information.

Officers are still battling a culture of people not talking to police due to fear of reprisal, he pointed out, but those who have come forward are making a difference.

"We need that information to get that direction and carry on with that investigation," Idsinga said.

You can watch the full interview with Insp. Hank Idsinga on CBC TV at 6 p.m. Thursday.