The son of a billionaire and his wife who were found dead in grisly circumstances five years ago has increased the cash reward for information surrounding the cold case. The couple’s son, Jonathon Sherman, told CBC Toronto that “closure will not be possible until those responsible for this evil act are brought to justice.” Jonathon has added C$25m ($US18.35m) of his own money to increase the reward to C$35m ($US 25.7) to help solve the case surrounding Barry Sherman and his wife, Honey, who were killed in their Toronto mansion on Dec. 13, 2017. Their bodies were found strangled in the basement pool of their home two days later, with belts looped around their necks while attached to a pool railing. “My parents deserved to enjoy the fruits of their labour, and spend their twilight years as any grandparent should, with their family. I continue to miss my parents more than I can describe, and I am forever haunted by what happened to them,” Jonathon said. Sherman, 75, was one of the world’s richest men as the founder and chairman of the board of drug giant Apotex. A suspect in the case is still yet to be named, though police say the investigation is ongoing. Toronto Police released CCTV of a person walking outside the couple's home the day they were killed, claiming the person captured on camera was a suspect.