Search for Missing American Abroad

(CBS)  A 22-year-old from Scottsdale, Ariz., has been missing in Germany for over a week, and, according to his father, no clues have yet been found that explain the young man's disappearance.

Devon Hollahan has been studying and teaching English in Prague, Czech Republic, but has not been seen or heard from since Nov. 21, when he traveled with a friend from Prague to Frankfurt, Germany, to see a concert and spend the weekend.

At around 3 a.m. that Saturday, his friend Josh Friedman, who had stopped to ask for directions, said that Hollahan vanished, CBS News correspondent Elizabeth Palmer reported from London.

"He had kind of a reputation for sort of disappearing," said Friedman. "So when I turned around and he wasn't there, that was my first thought - 'Oh, he did it again.'"

At first, Friedman said he wasn't too worried. But the next day, when Hollahan hadn't responded to any text messages or e-mails, then he started to get concerned.

Carrie Miltenberger, Hollahan's roommate, said that he never stayed out of touch for long.

"He has a wonderful relationship with his parents, and with me and his sister," she said. "He wouldn't do something like this."

Frankfurt police are now investigating and have appealed for information into Hollahan's disappearance.

His father, Jeff Hollahan, is going to Germany this weekend to help coordinate the search for his missing son.

So far, he told CBS News' Debbye Turner Bell, no clues have turned up.

"No clues, no credit card transactions, no cell phone activity, nothing at this point that would indicate to us that anything that might have happened," he said. "It's all pure speculation."

He also said that it's unusual for his son to fall out of contact with people. When Devon was in college, Jeff said the family spoke to him on a "fairly regular basis," though they were usually the ones who initiated the calls. When he went abroad, Jeff said, the communication became "even more regular."

No body has yet been found, and there has also been no activity on Devon's phone records. When asked if that news brought hope or worry, his father said that it gives him a bit of both.

"Not finding a body is obviously a positive," he said. "But it would be really nice if we had just a little glimmer of hope, a clue, anything at this point."