LOS ANGELES (AP) — The family of a mentally disabled man claims that the federal and local governments mistakenly had an American citizen deported and says U.S. officials should help find him in Mexico.

Relatives sued the Department of Homeland Security and the Los Angeles County Sheriff's Department on Monday in federal court, saying they have been searching for Pedro Guzman in Tijuana for a month.

"My worst fear is that he is no longer living," said Guzman's brother, Michael Guzman. "He doesn't know how to read. He often can't remember the family phone number. He even gets lost if he gets off the main street in Lancaster."

Pedro Guzman, 29, of the desert city of Lancaster, was sentenced April 19 to 120 days in jail for a misdemeanor trespassing violation, according to the lawsuit.

It says he was asked about his immigration status in jail and responded that he was born in California. Sometime after that, the Sheriff's Department identified him as a non-citizen, obtained his signature for voluntary removal from the United States and turned him over to U.S. Customs and Immigration Enforcement, a divison of the Homeland Security Department, for deportation.

The American Civil Liberties Union of Southern California, which helped file the lawsuit, has Pedro Guzman's birth certificate showing he was born at Los Angeles County-USC Medical Center, spokeswoman Celeste Durant said.

Sheriff's spokesman Steve Whitmore said the department followed procedures correctly.

"My understanding is that this individual said he was a Mexican national and was in the country illegally when we interviewed him," Whitmore said. "We turn that information over to immigration officials, who then re-interview him."

Immigration and Customs Enforcement confirmed he had been deported and said the agency had done so correctly.

"ICE only processes persons for removal when all available credible evidence suggests the person is an alien," read a statement. "That process was followed here and ICE has no reason to believe that it improperly removed Pedro Guzman." An agency spokeswoman declined to comment further because the lawsuit was pending.

Guzman called the home of his half-brother Juan Carlos Chabes in Lancaster on May 11, Michael Guzman said. He spoke briefly with Chabes' wife, telling her that he had been deported but that he didn't know where he was.

He asked a passer-by where he was, and Chabes' wife heard a man respond, "Tijuana," Michael Guzman said.

The phone cut off, and the family hasn't heard from him since, Guzman said. The family has put up fliers and visited police stations, jails, hospitals and morgues in Tijuana.

Federal agencies have denied the family help in finding him, said Catherine Lhamon of the ACLU of Southern California.

Pedro Guzman had previously done jail time for drug possession, so he had a record that could have been cross-checked before a deportation decision was made, Lhamon said.

Michael Guzman said that his brother was in special education classes before he dropped out of school, that he can't read or write, and that he has trouble processing information.

Michael Guzman said his parents were from Mexico, but seven children, including Pedro, were born in California. Pedro speaks both English and Spanish, he said.