TORONTO -- Ontario's ombudsman will probe what kind of direction the provincial government provides to police for defusing conflict situations in the wake of the fatal shooting of a Toronto teen.

The police shooting of Sammy Yatim, 18, raises the question of whether it's time for Ontario to have consistent and uniform guidelines on how police should de-escalate situations before they lead to the use of force, watchdog Andre Marin said Thursday.

"Are we going to look at improving the police response to this?" he said.

"It seems to be like Groundhog Day. Inquest after inquest. Police shooting after police shooting."

The province has the power to set standards for police training or procedures, he said, which was done in British Columbia following the death of Robert Dziekanski after he was stunned with a Taser by police.

Many coroner's inquests into similar deaths over the past 20 years have made recommendations that are almost "carbon copied from each other," he said, such as increasing police training.

"What's happened to all these recommendations in 20 years? Have they been gathering dust in some bin somewhere?" he said.

"When you look closer, these police shootings bear remarkable similarity to each other."

A coroner's inquest into similar police-related deaths will also get underway this fall.

Two men and one woman died of gunshot wounds between 2010 and 2012 after approaching police with edged weapons, the deputy coroner said Thursday. All three may have been suffering from the effects of a mental disorder at the time.

Marin said the investigation will look at how police are trained to deal with mentally ill people.

Community Safety and Correctional Services Minister Madeleine Meilleur said all police officers in Ontario receive use of force training as recruits and on a yearly basis as part of their in-service training.

"The ministry is conducting an ongoing use of force review that is examining officer training, the equipment they use and how use of force incidents are reported, and we will be looking at this very closely when working with the ombudsman's office," she said in a statement.

Marin said he's received more than 60 complaints, inquiries and submissions relating to the Yatim case. The investigation will take between six months to a year to complete.

Yatim was killed on an empty streetcar on July 27 in an incident that was captured on surveillance and cellphone videos, and sparked public outrage.

They show officers surrounding the streetcar and three shots being fired before Yatim is seen dropping to the floor. Seconds later six more shots can be heard, followed by the sound of a Taser.

Witnesses have told various media outlets that Yatim exposed himself and waved a knife around before the other streetcar passengers fled.

His death prompted hundreds of people to take to the streets calling for justice. More than 30,000 people have signed an online petition calling for criminal charges to be filed against the officer who fired the shots.

Shortly before announcing his investigation, Marin came under attack on Twitter, where he was called a "carded member of Al Qaida" among other insults. The same user also told Marin not to stick his nose in "business it doesn't belong."

The Twitter account was later deleted.

Marin called the tweets "deplorable" and said the tweeter was a Durham regional police officer. But that claim couldn't be immediately verified. The ombudsman wouldn't reveal how he'd identified the Twitter user, but said he would co-operate with a police investigation.

"Emotions run high when you talk about police oversight," he said. "Now in this case, it's a little higher than the normal temperature."

Durham police deputy chief Paul Martin said on Twitter that investigators would like any information Marin has on the origin of the tweets.

"We are investigating the disturbing allegations made by the Ombudsman regarding a DRPS officer," he tweeted.

Marin said he didn't believe the attack was related to his office's decision to launch an investigation.

"I've got thick skin," he said. "Like I said, it's part of the turf to deal with people who are upset. In this case, it's beyond that."

Marin said he's even had death threats in the last few months.

"I've dealt with a lot of types of situations, so nothing really surprises me at this stage."

The Special Investigations Unit -- Ontario's police watchdog -- is looking into the Yatim shooting and will decide if the officer who fired the shots should face any criminal charges. Marin said his investigation won't interfere in that work.

Toronto Police Chief Bill Blair has also said his office is reviewing the incident.

Const. James Forcillo has been suspended and the Toronto Police Association president has urged the public not to jump to conclusions.