SAN PEDRO (CBSLA) – Authorities Wednesday searched a San Pedro home in connection with the mysterious Northern California disappearance of 19-year-old Kristin Smart back in 1996.

An FBI spokesperson confirmed to CBS2 that it was assisting the San Luis Obispo County Sheriff’s Office with the search of a home in the 900 block of West Upland Avenue. A man who lives in the home, 43-year-old Paul Flores, is believed to be the last person who saw Smart alive.

The search warrant was one of four served by San Luis Obispo County Sheriff’s deputies Wednesday. Two others were in San Luis Obispo County and the fourth was in Washington state, the sheriff’s office said in a statement.

The sheriff’s office did not disclose why it was searching a San Pedro home and what it was hoping to find, except to say that it was looking for “specific items of evidence.”

“You have to have probable cause to issue a search warrant, so I’m not sure what they’re using,” Dan Payne, a retired FBI agent who once worked on the case, said.

In May of 1996, Kristin Smart of Stockton disappeared while a freshman at California Polytechnic State University. She was last seen leaving an off-campus party.

Flores, a student at Cal Poly at the time of Smart’s disappearance, is considered a person of interest in the case, according to the Sacramento Bee.

A man believed to be Flores was detained in a L.A. County Sheriff’s Department squad vehicle for two hours Wednesday morning outside the San Pedro home which was being searched. He was handcuffed, questioned, and then released by deputies after signing some paperwork. Video showed Flores running back into the home without answering reporters’ questions.

On Jan. 29, the sheriff’s office disclosed that it had taken two trucks into evidence that had belonged to family members of Flores back in 1996.

Last month, Smart’s mother, Denise Smart, told the Stockton Record that she was contacted by a retired FBI agent who told her to, “Be ready. This is really going to be something you don’t expect.”

Payne said that a break in the case could come as a result of improvements in DNA technology.

“Collection techniques and the amount of specimen you need has improved greatly since this case happened,” he said.