The son of a billionaire couple found strangled by belts by their pool is offering a $35m (£29m) reward for any information that leads to an arrest.
Barry and Honey Sherman were found hanged from a railing, side by side near a swimming pool at their £5.2million mansion in Toronto, Canada, on December 15 2017.
Five years later and there still have been no arrests.
On the anniversary of their killing, their son, Jonathon Sherman, announced he would more than triple the existing reward to encourage people to come forward.
Announcing the new money, he told Canada’s CBC News : “This week marks the five-year anniversary since my parents were murdered in their home. Every day since then has been a nightmare. I have been overwhelmed with pain, loss, and sorrow and these feelings only continuously compound."
He added: “Closure will not be possible until those responsible for this evil act are brought to justice.
“I hope for the day when I make this payment, as it will finally allow for healing.”
The bodies of the two were found by a realtor giving a tour of the couple's mansion.
They were discovered full dressed, seated side by side beside their indoor basement swimming pool.
They had belts round their necks which were attached to a poolside railing.
At the time of his death, Forbes estimated he was worth $3billion.
Although there was initial speculation it was a murder suicide, the family always vehemently denied this.
The family hired a private investigator to conduct an independent autopsy after complaining that police mishandled the case in its early days.
During a service for the two, Jonathon said: “Our parents never left anyone behind. They were taken from us."
Six weeks after the deaths, police announced they were likely murdered in a "targeted killing".
At the time Detective Susan Gomes would not say why it is believed the Shermans were "targeted".
Barry Sherman was 75 and his wife was 70.
There was no note found nor any sign of forced entry.
Their deaths stunned the worlds of Canadian business, politics and philanthropy, and drew public condolences from prominent figures including Canadian Prime Minister Justin Trudeau, who attended a memorial service on December 21 that was broadcast on television.
Barry Sherman founded Apotex Inc in 1974 and built it into a pharmaceutical giant before stepping down as chief executive in 2012.
