Homicide detectives are making a direct appeal to a "person of interest," seen accompanying a murder suspect in a surveillance video, to come forward with information about the shooting death of a Toronto millionaire.

Det. Sgt. Peter Moreira said at a news conference Wednesday afternoon that police are not sure how or if the man in the video was involved in the murder of Glen Davis on May 18, 2007.

"Enough time has passed and relationships change," Moreira said. "A relationship (with the suspect), if any, may have changed. This may be a motivator for this person to come forward."

Moreira also announced a $50,000 reward for information about the case.

Davis, a 66-year-old Toronto man well known for his generous donations to various wildlife causes, was shot in an underground garage in Toronto's midtown area.

He had just finished having lunch with a WWF associate when he was killed beneath the building that houses WWF offices on Eglinton Avenue, near Mount Pleasant Road.

Police believe Davis may have been targeted.

Moreira said despite receiving a number of tips from the public, the two people in the video have yet to be identified.

"The suspect may have bragged about this to people," Moreira said. "Any information the suspect may have shared we would certainly want to know about. (The reward) may be the thing that urges that person to through and contact the homicide squad."

Moreira said detectives had done a thorough background check on Davis and could not find anything that would explain his murder or a vicious beating he endured 18 months before the shooting.

Police didn't have a suspect in the beating. Investigators believe the incidents are connected but are still stumped on finding a motive.

The reward is the latest step homicide investigators are taking in an effort to spark public interest in the case.

In the months following Davis' death, police released images from a surveillance video camera showing two people of interest. They have also enlisted the help of the U.S. Federal Bureau of Investigation and other international law enforcement to help solve the case.