Investigators stand on the stair landing where the man's body was found early Monday. (CBC) A 25-year-old man was found dead on the river valley stairway next to the Hotel MacDonald in downtown Edmonton early Monday morning.

He had been living at an inner-city shelter and was last seen there early Sunday, police said.

Investigators found the man's body around 2 a.m. Monday near the Hotel MacDonald after someone called them to the scene.

The man appeared to have sustained trauma to the head, said city police Det. Bill Clark.

"We are treating it as a homicide at this time," he said. "Right now, our crime scenes people are on the scene and are conducting their examinations. We also have called out a civilian search team to assist with searching the brush area around the hill there for a weapon."

The man is believed to have been stabbed, Clark said. The suspect is believed to be aboriginal, between the ages of 14 and 20, with short hair and a thin mustache.

The stairs and the transit station across the street were blocked off with police tape to allow investigators to examine the scene.

The transit stop is closed. The area around McDougall Hill was expected to be cordoned off for the rest of the day.

Police are investigating a number of witnesses, Lisa Sobchyshyn, spokeswoman for Edmonton police said. They are also looking at security videos that may have been taken in the area.

An autopsy has been scheduled for Tuesday morning.

This is Edmonton's fifth homicide of 2010.