SALT LAKE CITY - When 30-year-old Paul Swenson didn't come home from an appointment in Salt Lake City on Thursday, his wife told police she was worried.

“She had told us at that point that he just wasn't acting himself, when he left, that he was sort of acting strange, didn't know if he was having some type of medical problem or if he was having a mental crisis,” said Sgt. Josh Christensen with the American Fork Police Department.

“He’s going through something, something's different,” said Ashlee Swenson.

Police did find his car near Parkview Elementary School in Salt Lake City. But, what they found inside only left friends and family more confused.

“Yeah we found a thing of alcohol that didn't belong to Paul, it wasn't, he didn't have that and so just random people's clothing and materials and things, so whoever was in that car it wasn't Paul,” said Cody Wilding, best friend of Paul Swenson and search party organizer.

“We've developed multiple theories and at this point we don't feel like there’s any one theory that’s been developed more than others just because of the lack of information,” said Sam Swenson, Paul’s brother.

Saturday, hundreds of volunteers gathered in South Salt Lake to get an assignment and go out and look for Paul.

“If you do see him, once again we're not exactly sure the state he's in: We'd recommend keeping an eye on him, contact your local authorities and if you can, keep an eye on him until they arrive,” Sam Swenson said.

Wilding said at this point they have more questions than answers in their search.

“Like, I don't want to say foul play, but, again, I know I keep saying I don't know: but the truth is we just don't know,” Wilding said.

American Fork Police would like to speak with anyone who might have information at (801) 794-3970.