The arrest of a 66-year-old landscaper in the presumed deaths of two gay men, who disappeared from downtown Toronto last year, stunned many in the city's LGBT community when the news broke on Thursday.

Bruce McArthur, of Toronto, faces two counts of first-degree murder in the deaths of Andrew Kinsman, 49, and Selim Esen, 44, who vanished close to Church and Wellesley, the city's predominantly gay neighbourhood, in 2017.

Homicide Det.-Sgt. Hank Idsinga told reporters McArthur and Kinsman were involved in a sexual relationship "for some time."

But the victim's sister, Patricia Kinsman, told CBC Toronto she had never heard of McArthur until police notified her of his arrest.

Toronto police Det-Sgt. Hank Idsinga says one man has been arrested and charged with the first-degree murders of Andrew Kinsmen and Selim Esen. 1:27

Court records show that McArthur was previously convicted for assault causing bodily harm in 2001.

McArthur, described by police as a self-employed landscaper, was on investigators' radar "for several months," Idsinga said. Though he declined to provide specifics, he said a recently uncovered piece of evidence led to the arrest.

Idsinga also said investigators believe there are other victims, and police have secured five properties — four in and around Toronto and one in the small community of Madoc, Ont. — linked to McArthur.

McArthur lived in a high-rise apartment in Thorncliffe Park, a leafy neighbourhood about five kilometres — a 15- or 20-minute drive — northeast of Church and Wellesley. Forensic investigators were examining a 19th floor unit there late Thursday evening.

One man, Kyle Andrews, who says he met McArthur once through a former boyfriend, told CBC Toronto in a series of brief Facebook messages that McArthur frequented Toronto's Gay Village.

Andrew Kinsman, 49, left, and Selim Esen, 44, right, are presumed dead. (Toronto Police Service)

He was also reportedly active on online dating sites. Someone named Bruce McArthur posted on the dating site Silver Daddies, which bills itself as a site for mature gay men, according to VICE Canada.

"I can be a bit shy until i get to know you, but am a romantic at heart," the profile, seen in a screen grab, reads. "I love to cook and enjoy most types of food."

McArthur was active on other social media. A Facebook profile with his name, and photos of a man identified by neighbours as McArthur, remains active.

On Facebook, McArthur is friends with another man who went missing from Church and Wellesley.

Skandaraj Navaratham, 40, known online as Skanda Nava, is one of three other men who vanished between 2010 and 2012. After he disappeared in September 2010, Abdulbasir Faizi,44, vanished from a location just blocks away three months later. Then, in October 2012, Majeed Kayhan, 58, was reported missing as well, last seen in the Gay Village.

McArthur was previously convicted of assault causing bodily harm in 2001. (Bruce McArthur/Facebook)

Those within the city's LGBT community previously questioned if a serial killer was responsible for the disappearances. All three men shared similar physical profiles and sexual orientations. Project Houston was established by police to probe the cases. Nothing ever came of the investigation, though last December, Toronto police warned residents to be careful while using dating sites to find partners.

Idsinga said the investigation into the presumed deaths of Kinsman and Esen, dubbed Project Prism, involved combing through information collected throughout Project Houston, though he didn't link McArthur directly to those cases.

And yet, Idsinga told reporters McArthur is thought to be "responsible for the deaths of other men who have yet to be identified."

McArthur is expected to appear in court in Toronto on Friday morning.