Billionaire philanthropist Barry Sherman and his wife, Honey, were murdered in their Toronto home by more than one killer, private investigators believe.

The finding, reported by CBC Toronto citing a source with direct knowledge of the private investigation, contradicts the theory that the deaths were a murder-suicide, a theory which has been rejected by the Shermans’ family and friends.

The couple’s bodies were found  hanging from a railing that surrounded their indoor pool on Dec. 15, 2017. Police labeled the deaths “suspicious.” The coroner ruled the couple died of strangulation. The investigation was turned over to Toronto homicide investigators.

There were no signs of forced entry into their Toronto-area home, which had been placed up for sale recently for an asking price of about $5.4 million. The bodies were discovered by the real estate agent, who let herself in with the key that had been given to her.

The Sherman family hired a team of experts, including former Toronto homicide detectives, to conduct a separate, independent investigation, according to the CBC.

The unnamed source told the CBC that though no rope was found on the premises, their wrists had been tied together at one time, and that the bodies had been moved at some point. Honey Sherman had cuts on her face consistent with a struggle with her killer, according to the report.

Barry Sherman was the 15th richest Canadian, according to Canadian Business magazine, with an estimated wealth of $4.77 billion Canadian, or $3.65 billion.

In addition to donating some $39 million to the United Jewish Appeal, Sherman was a fundraiser for Prime Minister Justin Trudeau’s Liberal Party.

Honey Sherman sat on the boards of several Jewish organizations, including Mount Sinai’s Women’s Auxiliary, the Simon Wiesenthal Center and the American Jewish Joint Distribution Committee.

The couple donated millions to local hospitals, schools and charities.