EDMONTON (CP) - Police stepped up their involvement Thursday in the search for a bright young man who vanished after he told his parents he was going to check out a music festival.

There have been no clues or tips about what may have happened to Robert Barrington Leigh, 20, who hasn't been seen since he left his family's home Sunday night on his mountain bike to visit the Edmonton Folk Music Festival.

About 100 friends and family have been searching the city's river valley since Tuesday. The Edmonton Police Service helicopter was brought in to do a sweep Wednesday.

But there has been no sign of the honours math and physics student, who has studied at the University of Toronto since 2003.

Missing persons detectives were expected to pick up the case next week, but on Thursday police decided to participate sooner.

Edmonton police spokeswoman Lisa Lammi said officers decided it was prudent to do so because records show Barrington Leigh's cellphone and credit cards haven't been used since he disappeared.

Four search dogs, several beat constables and five to eight patrol officers were being brought in to search the Mill Creek ravine, which the young man would have been biking through to get to the festival.

Members of the Search and Rescue Association were also joining the search.

His older siblings have flown in from Vancouver to create a missing person website, co-ordinate search efforts and design posters.

His family is putting out flyers in areas where "things are likely to be dumped."

The math wizard, who has won awards in several international math and physics competitions, has a straight-edge reputation that is well deserved, said his mother, Iris Barrington Leigh.

"We asked his friends and teachers about everything. It all checks out. He was fine. It's just too out of character for him to disappear," she said.

His friends have all told his parents their son doesn't do alcohol or drugs, and never discussed depression or suicide.

"We have that foul play feeling," his mother said.

Anyone wishing to help in the search is asked to visit findrobert.ca