The five men McArthur is accused of murdering — Soroush Mahmudi, 50, Dean Lisowick, known only to be in his mid-40s, Andrew Kinsman, 49, Majeed Kayhan, 58, and 44-year-old Selim Essen — vanished without a trace between 2012 and 2017.
Why McArthur allegedly killed the men remain unclear, Toronto Police Service Det. Sgt. Hank Idsinga tells PEOPLE.
“I don’t know what Bruce McArthur’s triggers were,” he says. “We’ll find out. The investigation is still ongoing and we still have victims to be identified and more charges to be laid. So hopefully we get some answers.”
Most of the men were known to frequent The Village, an LGBT-friendly Toronto neighborhood.
McArthur has yet to enter a plea.
Here are five things to know about the case:
1. Bruce McArthur Had Been Under Surveillance Since September
McArthur, 66, was arrested around 10:30 a.m. on January 18 at his high-rise apartment in Toronto and charged with the murders of Kinsman and Esen. The local landscaper had been under surveillance since September.
Then, on January 29, after serving at least four search warrants, police charged McArthur with the slayings of Kayhan, Lisowick and Mahmudi.
2. Police Searched Planters Where McArthur Worked — and Found Body Parts
After McArthur’s arrest, police began searching for bodies on a property where McArthur worked and stored landscaping equipment. Initially, police found the remains of three people in two of the planters. Police have since removed 15 planters from 30 different locations where McArthur worked around Toronto, and on Feb. 8, police announced they found three more remains in planters taken from the same property as they found the initial remains.
Some of the body parts are identified as belonging to Kinsman. Other than Kinsman’s, the remains have not yet been identified.
Police say they still haven’t figured out where McArthur allegedly dismembered the bodies. “The next question is where was he actually cutting these bodies up,” says Idsinga. “And I’m sure we’ll get and answer for that, but right now we just don’t know.”
3. Neighborhood Residents Long Suspected There Was a Serial Killer
Long before McArthur’s stunning arrest, regulars in Toronto’s Village knew something was wrong each time a new “Missing” flier went up. “We told police we thought it was a serial killer,” activist Alphonso King Jr. tells PEOPLE, “and they flat-out told us no.”
The disappearances began in 2010 when Sri Lankan immigrant Skandaraj Navaratnam, 40, disappeared after he was seen leaving a bar with an unknown man. That same year, Abdulbasir Faizi went missing from the Village, followed two years later by the disappearance of Kayhan. Police launced an investigation — dubbed Project Houston — in 2012 to look into the disappearances of Navaratnam, Faizi and Kayhan.
However, the investigation was closed in 2014 when investigators “couldn’t establish whether these gentlemen had met with any foul play,” says Idsinga.
Then, Mahmudi, a gregarious, married Iranian immigrant living in north Toronto, and Lisowick, who struggled with addiction and had fallen into the sex trade, went missing in 2015 and 2016, respectively.
In August of 2017, police launched Project Prism — a new investigation into the case — after Esen, a philosophy student and recovering drug user, went missing in April and Kinsman went missing in June.
4. McArthur’s Friends and Colleagues Are Shocked: ‘There Was Nothing Aggressive About Him’
News that McArthur is an alleged serial killer has shocked many who knew the outwardly gregarious landscaper. Friend Jocelyn Lemoine tells PEOPLE that he met McArthur about 16 years ago and spent a weekend with him in recent years.
“He was a really nice person,” he says. “There was nothing that could have showed me he would have a different personality. It makes you think. It is a question I ask myself what triggered him to do that to the others and not me. I don’t think I want to find out.”
Matthew MacKinnon, whose work overlapped with McArthur’s, says the alleged killer didn’t come across as “shifty or [like he] had something to hide.”
“He was easy to do business with,” MacKinnon says. “If you asked me a month ago if Bruce was a serial killer, I would have laughed at you. There was nothing aggressive about him. Nothing violent, nothing intimidating. I don’t think that guy could subdue me with a weapon. It is so weird. It blows my mind.”
5. Police Are Looking Into McArthur’s Past as a Traveling Salesman
McArthur grew up on a farm in the Kawartha Lakes, Ontario, area with his family. “They had 300 acres and some beef cattle and some pigs,” Robert MacEachern, who went to elementary school with McArthur near Woodville, Ontario, tells PEOPLE.
MacEachern says McArthur’s parents looked after foster kids while he was growing up. “It was a transient group,” he says. “Some came, some left. Some more came.”
By 1986, McArthur was married and living in Oshawa, and he later had a son and daughter. McArthur reportedly had money problems in the late 90s and declared bankruptcy in 1999.
Since McArthur’s arrest, police say they are looking into his past, including time he spent as a traveling salesman around Ontario.
“Depending on the evidence that we uncover here in Toronto, we will expand our enquiries and investigation into other jurisdictions,” says Idsinga.”We already have been contacted by other jurisdictions in regards to their outstanding murders and disappearances, and we remain cognizant of those while we continue our investigation.”
This article originally appeared on PEOPLE