Madrid, Spain (CNN) -- The family of an American college student who has been missing for more than a week in Madrid has hired private investigators from California to help search for him, the student's father told CNN on Monday.
A small team of investigators from the Halo Corp. is due to arrive in Madrid on Tuesday to search for the San Diego State University student, Austin Taylor Bice, who went missing after a night out with friends, said his father, Larry Bice.
Halo's website says it is a San Diego-based company "founded by former special operations and intelligence personnel."
"They are helpers," the elder Bice told CNN. "I don't want to give the idea that they are coming here running and gunning because they are not. They are coming to work with the police and do whatever they can."
The missing student, 22, has not been seen by friends since early February 26, when he told them he was going home, alone, while others stayed at a discotheque, family members and friends said.
Spanish police are investigating, and a U.S. Embassy official in Madrid has confirmed the missing-person report.
The student's father rushed to Madrid from San Diego last Wednesday and has since met several times with Spanish and U.S. authorities.
Friends of the student quickly organized a campaign to put up posters of him around Madrid, which read "Missing. Austin Taylor Bice. U.S. citizen, 22, 1.95 meters tall and 100 kilograms" (6 feet, 5 inches and 220 pounds).
The posters show Bice with a smiling, clean-shaven face, but he started growing a beard two weeks before he went missing, his father said.
The posters list two phone numbers -- a friend's cell phone and a police office line -- but the elder Bice said new posters will go up listing two national emergency phone numbers in Spain.
There is no indication of a kidnapping, and no demands have been received, his father said.
Austin Bice arrived in mid-January for a semester of business-course study at a Madrid university.
On February 25, he went out with five friends to a popular Madrid discotheque that doesn't open until midnight. He later left alone, early February 26, saying he was headed home, friends and family members told CNN.
A family member last Saturday told CNN that contrary to earlier reports, Bice was not refused entry to the discotheque by doormen and was not drunk, although "he had a few beers." Instead, he just decided to go home.
"We always told him, never be by yourself. Always be with somebody. And I think the problem was he got a little bit overconfident and decided that he wanted to go it alone, go back to the house by himself and that was the problem," said Juan Gabriel Paredes, a family member who came to Madrid from Wichita, Kansas, to help Bice's father in the search.
Paredes said four of Bice's friends went into the discotheque while Bice and another friend remained outside. Eventually Bice decided to go home alone.
Dozens of Bice's friends and others responding to internet notifications conducted a search last Saturday, starting from the discotheque, La Riviera, on the banks of the Manzanares River, down a hill and removed by many blocks from the city center.
"I just want to say thank you for all being here. It's hard for me to talk about it, but thank you," Bice's father told the search teams, his voice cracking.
"People we've talked to say if it were bad, it would have shown up right away," Bice's father told CNN on Thursday in an off-camera interview. "It's easier being here than at home. I see what's going on."
The student was carrying two credit cards and his California driver's license, his father said.
Calls to two cell phones Bice was carrying the night he went missing have gone unanswered, his friends said.
The weekend search teams split into four-member groups and fanned out, some heading across the river to a large park, others walking up Calle Segovia toward the city center, where friends said Bice was last seen.
The search teams posted more missing-person posters and entered stores and other establishments to ask people if they had seen anything. Some responded that they had seen the news of the missing student on Spanish media.
The U.S.-based Institute of International Education said that in 2007, Spain was the third most-popular destination worldwide for Americans studying abroad, after the United Kingdom and Italy. It said there were about 17,000 American students in Spain.
Bice was studying in Madrid at the University of Carlos III, which has 18,000 students, including about 220 Americans, the school's director of international relations, Carlos Lopez Terradas, told CNN.
His father said, "It's been hard, real hard. These are the things you hope never happen to you."
He added he would remain in Madrid to follow the search for his son "as long as I need to."