Toronto police ask for help identifying ?highly suspicious? person in billionaire murder case

Four years after the unsolved murders of pharmaceutical billionaires Barry and Honey Sherman, police in Toronto have appealed to the public to help identify a possible suspect in the case.

At a media briefing on Tuesday, homicide DS Brandon Price said police had studied hours of CCTV footage taken in the couple's neighbourhood the night of the murders and had identified all people caught on camera - except for one person.

"We have been unable to determine what this individual's purpose was in the neighbourhood," Price said. "This individual's actions are highly suspicious."

Police believe the lone figure walking along the street on a snowy night is linked to murders of Barry Sherman, the founder of drug giant Apotex, and his wife Honey. The couple were found dead in the basement pool area of their home in late 2017, with had belts looped around their necks and attached to a pool railing.

There were no signs of a break-in at the couple's house, and police initially believed the deaths to be a murder suicide. But investigators later determined the couple were victims of a "targeted" double homicide.

The footage released Tuesday marks the first time in nearly four years police have updated the public on the investigation.

The poor quality of the video means the the skin colour, weight and gender of the suspect are not known. Police say video analysis suggests the individual is between 5'6 and 5'9 tall. The suspect, who has an unusual gait, walks into an area not captured by any video surveillance, stays for a "suspicious" amount of time, and then leaves.