Police in Ontario are continuing to investigate what exactly led to a series of slayings involving a woman they are calling an alleged “serial killer.”

Over a span of three days last week, three people were killed by the same suspect in three different incidents in Hamilton, Niagara Falls and Toronto.

On Friday, three Ontario police forces announced they had charged a 30-year-old Toronto woman with murder. Niagara Regional Police Chief Bill Fordy told reporters Oct. 4 that by “by definition, she is a serial killer.”

The investigation is ongoing, and police are seeking the public’s help in putting together the pieces to get a better understanding of what happened over those three days.

Here is what we know so far.

Killings began in Toronto

The streak of slayings began on Oct. 1 in Canada’s largest city.

Just after 2 p.m. that day, Toronto police said they responded to a call for service at a home near Keele and Dundas streets. When they arrived on scene, they found a woman dead with signs of trauma on her body.

Click to play video: 'Toronto woman charged with 3 murders in 3 days across Ontario: ‘By definition she’s a serial killer’'

The following day, on Oct. 2, Niagara Regional Police said they were called to John Allan Park in Niagara Falls just before 3 p.m. for reports of a disturbance.

When they arrived, officers found a man suffering critical injuries who, despite the attempts of first responders, died at the scene.

Finally, just after Noon on Oct. 3, Hamilton police rushed to a parking lot off MacNab Street North where they found a man who had been stabbed. Police said he was taken to hospital, where he died.

It wasn’t until Oct. 4 when police announced an arrest and made a link to the cases.

Who is the suspect?

On Friday, investigators with Toronto police said the detectives’ working understanding was that the Toronto victim was known to the woman, while the two other deaths were believed to be “randomly targeted.”

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Toronto police said detectives involved were able to “link the homicide” in Hamilton with the death in Niagara Falls.

“An additional link was made to the active homicide investigation from Oct. 1 in Toronto,” the force said.

30-year-old Sabrina Kauldhar has been charged with three separate homicides.

30-year-old Sabrina Kauldhar has been charged with three separate homicides.

NRP / Handout

The accused was identified as Sabrina Kauldhar, a 30-year-old woman from Toronto. She faces a second-degree murder charge in Toronto, and two first-degree murder charges from Niagara Regional Police and Hamilton police.

Fordy said investigators were able to use video footage to identify Kauldhar before she was eventually arrested just before 6 p.m. Thursday in Burlington, Ont.

He added Kauldhar arrived at a hotel investigators were securing, and was taken into custody. Fordy would not comment on if she was staying there.

She is in the custody of Niagara Regional Police. Kauldhar appeared in court on Friday.

Hamilton, Niagara victims were ‘going about their business’

Global News has learned the accused was roommates with the Toronto woman who was killed. She is believed to be in her 60’s and has yet to be identified.

The victim in the Niagara Falls killing was identified as 47-year-old Lance Cunningham, while the Hamilton stabbing victim was named as 77-year-old Mario Bilich.

“Mario and Lance Cunningham were both going about their business and we believe that they were random attacks,” Fordy said.

“We are not aware of any connection between the victims and we are not aware of a motive at this time.”

Friends and family confirmed that Bilich was a retired teacher.

Calogero Milazzo, a friend of Bilich’s, said he was shocked.

“He was an ex-high school teacher, he knew many languages, he was brilliant,” he told Global News.

“A friendly guy, happy-go-lucky, five kids, everything.”

In a post on Facebook, Bilich’s daughter said her father had died in a “senseless stabbing” in the city.

“Please pray for us, his children, in-laws, grandchildren, sisters-in-law, nieces and nephews here in Canada as well as his many cugini e zii in Italy and Croatia and France,” she wrote in her post.

Investigators ‘trying to better understand’ timeline

On Friday, Fordy said it was hard to guess if the slayings would have continued had the suspect not been arrested.

“What I can say is I am very pleased that we were able to bring this to closure in a quick manner,” he said.

“We have three families who have lost their loved ones, and I think, if someone has committed three offences in a time frame like that, there is a risk of them committing further offences.”

Police said they are particularly concerned with anyone who may have seen Kauldhar between Oct. 1 and her arrest just before 6 p.m. on Oct. 3, and are asking anyone with information to come forward.

“Our investigators are in the throes of trying to better understand the timeline,” Fordy said.

Anyone with information is asked to contact police in either Hamilton, Niagara or Toronto.

— with files from Isaac Callan and Catherine McDonald