LOUISVILLE, Ky. – A man who pretended be a boy who disappeared in 2011 pleaded guilty Wednesday to aggravated identity theft.

The charge, filed in federal court in Cincinnati, carries a mandatory two-year prison term, although Brian Rini will be formally sentenced at a later date.

Rini, 24, with a neatly trimmed beard, answered U.S. District Judge Michael Barrett with a soft “Yes, sir,” when asked whether he understood the consequences of his plea.

Prosecutors dropped charges of lying to FBI agents.

On April 3, the native of Medina, Ohio, was found wandering on a street in Newport, Kentucky. He claimed to be Timmothy Pitzen, a boy who had been missing for eight years. Rini, who is 5-foot-9, was clean-shaven at the time. Timmothy now would be 14.

That day at Cincinnati Children's Hospital Medical Center, Rini told an investigator he recently escaped from a hotel room where he had been held captive by two men.

Rini, who knew the missing boy's full name and date of birth, said "he had been sexually and physically abused for years while in captivity," according to newly filed court documents.

The next day, he told an FBI agent essentially the same story, the documents say. Rini said he had been forced to have sex with men against his will.

Rini eventually admitted he had been lying. He had learned about Timmothy on the television show "20/20."

At an October hearing, Rini was found mentally competent to stand trial. Rini's federal public defender had described him as having "a significant mental health past."

Brian Rini knew the name and birth date of Timmothy Pitzen when he was charged with impersonating the long-missing boy.

Rini was evaluated at a federal prison in Chicago, and a doctor found that he understood the legal proceedings and could help in his own defense.

The competency report said Rini has "some symptoms of depressive disorder, which are in remission," according to a transcript of the October hearing. "But he does not appear to be suffering from any severe mental disease or defect."

Timmothy Pitzen is a Chicago-area boy who disappeared in 2011, when he was 6.

Rini, who grew a beard after his arrest, was at Children's Hospital for more than a day, according to court documents. But after being confronted with DNA test results, he admitted his true identity. Asked why he claimed to be the missing boy, Rini said "he wished he had a father like Timmothy's," according to the documents.

Rini's criminal record dates back to when he was 13.

Officials said he twice before has claimed to be a juvenile victim of sex trafficking.

Contributing: The Associated Press