Police in Barrie, Ont., said Wednesday that a witness spoke to a 15-year-old boy on the day he went missing after an argument with his parents over his Xbox.

Sgt. Dave Goodbrand said a woman has come forward, saying she spoke with Brandon Crisp on Monday, Oct. 13 and that she noticed he was having trouble with his bicycle. Police found the bicycle in a ditch northeast of Barrie later that day.

"We've confirmed that a person walking in the area on the path on the day he was missing did in fact speak to him and confirms that he was here, and he was having problems with his bike at the time," Goodbrand told The Canadian Press.

"We're focusing (the search) here because it's really the only concrete evidence we have to his possible whereabouts."

Brandon's parents fear their son may have become mixed up with people he met while playing video games online. The teen has been missing since Oct. 13 when be became upset and left his parents' house after they confiscated his gaming system.

His mother called the situation "every parent's worst nightmare."

"It's terrifying," Angelika Crisp told CTV's Canada AM from their home in Barrie. "And we think he might have met someone online through this game that he befriended and got himself into a lot of trouble he wasn't expecting, and might be in danger now."

Brandon's father Steve Crisp said the couple becomes more anxious with each day that passes.

"The fact we haven't heard a single thing in 10 days now is distressing," he said.

Brandon had become addicted to the game "Call of Duty 4: Modern Warfare," his parents said.

He skipped school on the Thursday prior to Thanksgiving weekend, causing his parents to revoke his Xbox privileges -- a disciplinary measure they had used, his father said.

"We had basically taken his Xbox away. He took it back, and the catalyst for this was I took it away for good the second time and at that point, that was when he said he couldn't handle it anymore, he said he was leaving," said Steve Crisp.

Brandon's friend said he is dismayed his friend ran away from home.

"We are all in shock because he just isn't the type of guy who would run away," said Zach Frechette.

An intensive search operation has been underway in the Barrie area since Crisp was reported missing.

Three teams conducted ground searches Wednesday in the 2nd Line area of Oro-Medonte along an abandoned railway line where Crisp's bicycle was last seen. Police concluded their search Wednesday evening and will resume Thursday morning.

Police still have little to go on, Goodbrand told CTV Newsnet on Wednesday.

"No information has come in that has led us in the direction of where Brandon could possibly be, so the only concrete piece of information that we do have that we've confirmed is where his bike was located. So we do have some reason to believe Brandon was there sometime after he left home so we're going to continue to search that area today," Goodbrand said.

Crisp was last seen riding away from home on a yellow and black mountain bike at about 3 p.m. on Oct. 13 after asking his parents for directions to Shanty Bay.

Police have been tracking the teen's user name on the online Xbox account but said he has not logged in.

His parents described him as an average teenage boy and said he has never done anything like this before.

"He's a great kid," Angelika Crisp said. "He's a little bit shier than some kids but he's always been a great kid -- good at school, loves sports, or he used to love sports before he got addicted to this game."

Goodbrand said Crisp comes from a good family and running away is simply out of character.

"He's a little introverted, he only has three or four core-group friends and those are the people he plays with on the video game network. But no, he's never run away before, he's well received at the school," Goodbrand said after speaking to school administrators and teachers.

"There's lots of missing kids out there but this particular case is unique because Brandon is not the type to run away, especially for this period of time."

Brandon's friends at his Barrie high school started a graffiti wall where everyone has written a message to him, praying for his safe return.

Barrie police, along with members of the Crisp family, will be participating in a Ceremony of Hope being hosted by the staff and students of St. Josephs Secondary School, according to a Barrie Police news release. The event takes place on Cundles Rd in Barrie tomorrow morning at 8:30 a.m.

Police have asked locals to search their residences and cottages for any sign of Crisp.

He is described as male, white, 100 pounds, 5'2", with short sandy blond hair. When he was last seen, he was wearing a yellow and grey jacket, a grey American Eagle-brand hoodie, blue jeans, white runners with a camouflage stripe on the sides. He may also be carrying a yellow and grey back pack.

Anyone with information is asked to contact Barrie police at 705-725-7025.

With a report from CTV Toronto's Dana Levenson