Steve Whitmore told The Associated Press on Monday that investigators "positively identified" Christian Gerhartsreiter as the man being held in Boston and wanted for questioning in the disappearance of Jonathan and Linda Sohus.
Whitmore says Gerhartsreiter went by the name "Christopher Chichester" when he lived at the Sohus property at the time they went missing. He was recently using the pseudonym "Clark Rockefeller" when arrested for allegedly kidnapping his daughter in Boston.
Investigators have requested new forensic tests on skeletal remains found at the Sohus property.
Rockefeller's attorney says his client can't remember anything in his life prior to his 1995 marriage, reports CBS News correspondent Kelly Wallace, but prosecutors in the kidnapping case aren't buying it. They're calling Rockefeller more of a schemer than someone having trouble with memory.
The bespectacled 48-year-old has been jailed since being accused of abducting his daughter from Boston's high-society Back Bay neighborhood.
Rockefeller's attorney, Stephen Hrones, said he advised his client not to speak to the Los Angeles investigators. He said Rockefeller "denies absolutely" any connection between him and the California case.
In 1985, Jonathan and Linda Sohus disappeared without a trace fom the wealthy Los Angeles suburb of San Marino.
Sohus' mother reported receiving postcards from her son in Paris, and died in 1988, thinking her son and daughter-in-law had moved to Europe and forgotten about her.
Then in 1994, the new owners of the Sohus property were digging a swimming pool when a backhoe uncovered human remains in three plastic bags. Investigators also found horse and chicken bones.
The badly damaged remains were believed to be those of Jonathan Sohus but were never positively identified, said Lili Hadsell, a former San Marino police sergeant who took the initial missing persons report.
Jonathan Sohus was adopted, so there was no obvious way of comparing the bones' DNA to that of family members, half-brother Chris Sohus said.
Policed believe "Rockefeller", now known to be Christian Gerhartsreiter, also was a man who went by the name Christopher Chichester, who was a tenant of the Sohus'. Police explored various possibilities, including that Chichester had been in love with Linda Sohus and murdered her husband in a fit of jealousy.
According to a 1994 sheriff's department press release, Chichester was described as a con man who "surfaces in affluent neighborhoods and mingles in social circles by making friends with wealthy, influential people," a similar portrait of the country club lifestyle of Rockefeller.
Authorities came close to Chichester in the late 1980s when he was pulled over in Greenwich, Conn., driving Sohus' truck. But by the time the Department of Motor Vehicles had confirmed it was Sohus' truck, Chichester and the vehicle had vanished.
"We were very diligent in trying to track down as many leads as we could, but they were adults, and there were no signs of foul play," Hadsell said of the initial investigation. "Adults can go ahead and disappear."
Neighbors in San Marino remembered Chichester as a smooth talker who was well-dressed and seemed well-educated. He did all the right things to ingratiate himself with his upscale neighbors, including volunteering at the local library, said Ray Cornwall, a neighbor who has lived in the community since the 1970s.
"He's a prototype con man. He's really good at it," said Cornwall, whose daughter dated Chichester briefly in the mid-1980s. "It's going to be hard to prove anything, because he's not left any permanent trail. It's all smoke and mirrors."