An American college student who apparently suffers from psychological problems has confessed to killing an Italian man in Florence, police said Friday.

Lead investigator Filippo Ferri said Johnathan Robert Hindenach, 24, of Charlotte, Michigan, had consumed drugs and alcohol before the slaying early Thursday.

Hindenach was detained near the storefront where police discovered the body of 62-year-old Riccardo Nistri. Nistri's relatives had alerted police to his disappearance after they called his cell phone and an American in a "confused state" answered, investigators said.

Police don't have a motive, but Ferri said Hindenach fled the hotel where he was staying with a group of students Wednesday night, saying his colleagues wanted to kill him.

Ferri said Hindenach had confessed to the crime after police questioned him. He said the man suffered from some type of psychological problems and had cut himself with a broken piece of a mirror after the slaying.

After being taken to the hospital, Hindenach was taken to a Florence prison, where he remained in detention pending a hearing to confirm the arrest, Ferri said.

Hindenach's court-appointed attorney, Maristella Taggi, declined comment Friday, saying she was working with the U.S. Consulate to determine if Hindenach would hire his own attorney.

People who answered the phone at a Charlotte listing for a Johnathan R. Hindenach hung up on AP reporters Thursday night and Friday morning.

Florence police spokesman Gianpaolo Monastra said Hindenach had been in Italy for 16 days, along with a group of students and teachers on vacation, but not for a study abroad program.

It wasn't immediately clear if Hindenach was an undergraduate or graduate student; police said they didn't know the university name or program he was on.

An American college student, Amanda Knox, is currently on trial in the central Italian city of Perugia, charged with sexual violence and murder in the 2007 slaying of her roommate. Knox, who was on an exchange program in Perugia, has denied wrongdoing, as has her former boyfriend who is accused of the same charges.