FRANKFURT (CBS/AP) The father of American English teacher Devon Hollahan, who went missing in Germany more than a week ago, is "terrified" by his son's disappearance.
"Unfortunately, still no major clues in the case, but they're still hard at it," Jeff Hollahan told the Associated Press in a telephone interview Monday about the mystery surrounding his 22-year-old son.
The younger Hollahan had been teaching English in Prague since July.Video: The Early Show.
He was last seen at around 3 a.m. on Nov. 21 after a concert in Frankfurt.
Devon Hollahan was traveling back to a hostel with a friend, who stopped to ask for directions.
When the friend turned back around, Hollahan was gone.
Jeff Hollahan, of Scottsdale, Arizona, arrived in the German city Monday and met with the primary investigators, with whom he had spent much of last week with on the phone.
He said they showed him what they know and maps depicting where the two young men were that night.
But there are more questions than answers so far, he said, adding that there's not much to go on except "rank speculation," he said. "The police deal in facts."
The elder Hollahan, added that "It's frustrating. He's a good kid and it just still seems odd to me that he just sort of dropped off the face of the planet in the middle of a busy European city."
The U.S. Consulate in Frankfurt is working to locate Devon, too, spokeswoman Jeanine Collins said.
"The U.S. Consulate in Frankfurt is fully engaged with Devon's family and the German police both in diplomatic and consular posts in a cooperative effort to locate Devon," she said. "The U.S. State Department's highest priority is the welfare of U.S. citizens abroad."
Manfred Fuellhardt, a spokesman for Frankfurt police, had scant information.
"Unfortunately, there's nothing new for me to say," he said.