The family members of a 23-year-old man who went missing in northern Minnesota aren't returning to their Wisconsin home without him, his fiancée said Saturday.

Ty Sitter of Janesville, Wis., hasn't been seen since Thursday, when he left his father and brother at their campsite on Swan Lake to go fishing in the Boundary Waters Canoe Area Wilderness, 15 miles northwest of Grand Marais.

The Cook County Sheriff's Office, U.S. Forest Service and a State Patrol helicopter began a search Friday and continued combing the area Saturday with 20 people and six dogs.

Sitter's father and 19-year-old brother are helping with the search, fiancée Cassandra Powell said, and "they're not coming out until they find him."

Meanwhile, she's in Janesville, some 10 hours away, waiting for word about her boyfriend of nearly two years.

"I completely lost it; I was in total shock," she said of the news of his disappearance. "I'm still very, very concerned."

She's also trying to hold out hope, after authorities told her that a dog picked up a live scent Friday.

Sitter, an avid outdoorsman and motorcycle mechanic, has camped in the northern Minnesota wilderness since he was young. The Boundary Waters trip with his father and brother is an annual tradition, Powell said. "He knows how to survive," she said.

He was last seen at 7 p.m. Thursday on Swan Lake, going off to fish by himself.

When he didn't return to their campsite by 9 p.m., his father and brother began to look for him, finding his canoe upright and unoccupied on the lakeshore. It was filled with 4 inches of water, but had everything Sitter left with -- a life jacket, fishing net, tackle box and rock anchor -- except his fishing pole. According to the Cook County Sheriff's Office, the two paddled out and alerted authorities at midnight; a search began immediately.

Powell said she remains concerned but hopeful about the fate of her husband-to-be, who she thinks may have docked the canoe on land to fish when it floated away as rain moved in Friday. Sitter had knee surgery 2 1/2 weeks ago, but Powell said she doesn't know if that was a factor in his disappearance.

"He's not the type of person to sit there and wait for someone to get him, so he might have tried to walk," she said.

According to the Sheriff's Office, water cadaver dog teams and personnel are also assisting with the search by the Minnesota Department of Natural Resources, Grand Marais First Responders, U.S. Forest Service, Life Link III and Civil Air Patrol. The St. Louis County Sheriff's search and rescue unit is assisting with a side scan sonar and underwater camera.

Kelly Smith • 612-673-4141