Barry Sherman, 75, was found dead in his Toronto home with Honey Sherman, 70.
Police released a brief clip of an individual who was walking near Sherman's house on the night they were shot and killed.
Police have not been able to identify this person who was captured on video footage near the scene.
Sgt. Brandon Price, the lead detective of the investigation, stated that the suspect entered a "well-defined region, tight around Sherman property" on Tuesday 13th December 2017, the night police believe the murders occurred.
When asked by reporters why the suspect was not a person of concern, Sgt Price replied: "We have this person coming into a very specific area... and staying in that area for some time before leaving."
He stated that "we have been unable find a reason" for the suspect to be there and added that his actions were "very suspicious".
Police are asking anyone with any information to identify the suspect to come forward. They estimate that the suspect is between 5ft 6in to 5ft 9in tall and have a distinct gait. However, they are unable to confirm their gender, age, weight or skin color.
The mystery behind the strangled billionaires
Barry Sherman, one of Canada's most powerful men and the founder of Apotex generic drug manufacturer, was one of Canada’s wealthiest men. His wife, Barry Sherman, was a well-known philanthropist who donated millions to Jewish institutions, universities, and hospitals.
On 15 December, the couple was found strangled to death in their Toronto home. They were both covered by the indoor pool deck. The police said that there were no signs of a break in.
Both had died of ligature neck compression or strangulation with materials, according to autopsies.
Police stated that the Shermans were victims of double homicide in January 2018, six weeks after they were found.
Police have conducted around 250 witness interviews since Sherman's murder and received 1,255 tips. They also obtained 41 warrants.
Sherman's family has criticized the police handling of this investigation and offered a C$10m (7.8m; PS5.88), reward for information leading towards the arrest and prosecution a suspect in 2018. Police said Tuesday that the reward for Sherman was still available to the public.
