Investigators are conducting DNA tests on an unearthed skeleton and examining remnants of a blood stain that may be related to the case of a missing California couple in which a Massachusetts kidnapping suspect has been named a "person of interest."

The bones are thought to belong to Jonathan Sohus, who with his wife Linda disappeared in 1985 when a man now known as Clark Rockefeller was a tenant in their family's San Marino guesthouse. The bloodstain was found in the guesthouse soon after the bones were unearthed.

Though Sohus matched the general description, investigators were unable to definitively identify the bones because Sohus was adopted and his dental records were lost.

There are no known biological relatives, so investigators have sent DNA from the bones to a national database in hopes of finding a match, said Ed Winter, assistant chief of the Los Angeles County coroner's office.

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The bones were discovered in 1994, nearly 10 years after Sohus and his wife disappeared, when contractors were digging a hole for a swimming pool. Wrapped in several small shopping bags tied together with twine, the remains were buried about 4 feet deep and close to the guesthouse, said Tricia Gough, a detective with the San Marino Police Department at the time.

"I feel pretty certain it was John Sohus," she said. "The physical similarities were very striking."

Gough said that a few months after the bones were found, investigators detected blood in the guesthouse that was too degraded to tell whether it was from a human or an animal.

The remnants of the stain will be "one focus" of the new investigation and analyzed again, Los Angeles County sheriff's spokesman Steve Whitmore said.

"All evidence that was collected back in '85, back in '94, and evidence that has been recently collected by way of interviews and everything else will be examined with every modern technology we have available to us," Whitmore said.

Sohus and his wife had shared the home, about 10 miles northeast of Los Angeles, with Jonathan's mother. After the disappearance, she moved away, and the home's new owners refurbished it.

Rockefeller was arrested Aug. 2 in Baltimore after allegedly kidnapping his daughter from Boston during a supervised visit.

The Los Angeles County Sheriff's Department has said Rockefeller is really Christian Karl Gerhartsreiter. A man of many aliases, he was known as Christopher Chichester while living in California.

No one has ever been charged in the Sohus case, and Rockefeller has denied any involvement in the couple's disappearance.

DNA analysis was not carried out in 1994, Gough said, because the technique was not widely used at the time.

The remains dug up in 1994 included a nearly complete skeleton, with only a couple of small bones missing, Gough recalled. The skeleton was clothed in socks, a flannel shirt and jeans, and appeared to have been hastily wrapped in the bags, she said.

"It was like if you or I were to commit a murder and say, 'Oh my goodness, what have we done?"' she said. "Like someone had run round the house and picked up lots of different plastic bags."

Sheriff's officials said late Wednesday that they would not release any other information on the investigation, perhaps until the case is solved.

"Detectives have decided there's too much information out there," Whitmore said.