Police have issued a public appeal for cellphone photos and video of a deadly assault on an 18-year-old Calgarian.

Lukas Strasser-Hird was stabbed in an alley near 10th Avenue S.W. on Nov. 23. Three men were charged with murder in connection with his death.

Calgary detectives say some people may have evidence on their cellphones that could lead to a conviction. 

"It is believed the victim was involved in two altercations prior to his death. Following the first incident, the victim and his associates were separated from the situation, but a short time later the groups re-engaged near the rear of a downtown bar," police said in a release.

"Investigators believe that some onlookers may have used their cellphones to video or photograph either or both of the altercations. These images may have been shared and police are keen to obtain them as the investigation continues."

A special email address is now set up to receive photos and video at homicidetips@calgarypolice.ca

Photos can also be sent anonymously through the Calgary Crime Stoppers web page.