LOS ANGELES — A man charged with kidnapping his daughter in Boston is a German who lived in the guesthouse of a Los Angeles-area couple who disappeared in 1985, a sheriff’s spokesman said yesterday.

Los Angeles County sheriff’s investigators have identified Christian Gerhartsreiter as the same man who used the aliases Clark Rockefeller and Christopher Chichester, a spokesman, Steve Whitmore, told the Associated Press.

Homicide detectives “are confident that Rockefeller is Christian Gerhartsreiter and the person named Christopher Chichester who was living in the Los Angeles area in 1985,” Mr. Whitmore said.

Gerhartsreiter has been identified as a “person of interest” in the 1985 disappearances of Jonathan and Linda Sohus. Under the Chichester name, Gerhartsreiter rented a guesthouse at the couple’s home in San Marino, a wealthy Los Angeles suburb.

Investigators were able to confirm Gerhartsreiter’s identity after interviews with people who knew him in California in the 1980s, Mr. Whitmore said.

At the time of his August 2 arrest in Baltimore, Gerhartsreiter had been living under the Rockefeller name. Police have said he snatched his daughter from a Boston street on July 27 in an elaborately planned kidnapping in which he hired two people to drive them to New York.

The district attorney’s office and FBI in Boston said yesterday they were not ready to declare that Rockefeller and Gerhartsreiter are the same person.

In the San Marino case, skeletal remains were unearthed at the Sohus property in 1994 when new owners were putting in a swimming pool. Investigators at the time were unable to identify the bones but believed they probably belonged to Jonathan Sohus. Investigators have requested a new round of forensic tests, Mr. Whitmore said.

Two women who were friends with Christopher Chichester in the mid-1980s told the Los Angeles Times they noticed that much of the backyard at the Sohuses’ home had been dug up around the time they disappeared. Chichester told them there had been plumbing problems.