Toronto police have enlisted the help of the U.S. Federal Bureau of Investigation and other international law enforcement, to help solve the murder of millionaire philanthropist Glen Davis.

The FBI is enhancing images of a person of interest and a suspect who were captured on video surveillance equipment as they left the building where Davis was killed.

Davis, 66, was shot to death in an underground Toronto parking complex on May 18.

International alerts have been released by Interpol and the RCMP, and Crime Stoppers has distributed posters and web postings in Canada and the U.S.

Police have been investigating Davis' murder for months without any new leads.

"We're still waiting for that tip to come through that will help us identify these two people that we're looking for," Det. Wayne Fowler told CTV News.

Investigators have also uploaded the video to the popular file sharing website YouTube in the hopes of enlisting international tips.

"If these people were living in Toronto -- and known in the community in Toronto -- I'm sure there would be more tips locally regarding the identity of these two people. Especially now where the video has been released linking these two people together," Fowler said.

The parking garage where Davis' body was found was used by an exclusive group of attendants, visitors and restaurant patrons, police said.

Authorities believe Davis was targeted for the crime, but a motive is still not yet clear.

Davis, described as shy and quiet by friends, donated millions of dollars to various wildlife causes.

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

Investigators are also trying to determine if a baseball bat beating he sustained in December 2005 is somehow linked to his murder.

With a report from CTV's Janice Golding