ANTIOCH, California (CNN) -- A bone fragment found near the northern California home of kidnapping and rape suspect Phillip Garrido could add another chapter to the twisted tale.
Cases of missing girls Ilene Misheloff, left, and Michaela Garecht now linked to Garrido investigation.
On Tuesday, authorities will try to determine whether the bone is human and whether it connects Garrido, 58, to any crimes beyond the alleged kidnapping and imprisonment of Jaycee Lee Dugard, who went missing in 1991 at age 11.
Investigators said they found the bone on a neighbor's property in an area to which Garrido had access.
Crews were using cadaver dogs to search the property, said Jimmy Lee, a spokesman for the Contra Costa County Sheriff's Department.
Investigators are looking into other cases that may involve Garrido, giving hope to parents including Sharon Murch, whose daughter, Michaela Garecht, was abducted at age 9 in 1988.
"I leaped up yelling, 'Oh, my God.' I was, of course, joyful for Jaycee herself, but my first thought was 'please, God, let Michaela be with her,'" she said.
"I was very high for a while. I was very low for a while." Watch Murch describe the cases' similarities »
Garrido kidnapped Dugard in 1991 in South Lake Tahoe, California, fathered two daughters with her and held her captive in a well-hidden backyard compound, authorities said. Watch aerial view of backyard compound »
Garrido and his wife, Nancy, face 29 felony charges, including rape and kidnapping. Both have pleaded not guilty. Watch what investigators say about bone fragment »
Dugard has begun the process of getting to know her mother again, said her stepfather, Carl Probyn.
"She's doing good," Probyn told CNN's Larry King on Monday. "She's with a group and they're taking care of her and they're getting adjusted."
Dugard is with her mother at an undisclosed location along with a team of psychologists and law enforcement officers, he said. He has not seen or spoken to his stepdaughter. The last time he saw her was 18 years ago, when he watched helplessly as she was kidnapped at a bus stop near the family's home. See photos of Dugard's living conditions »
FBI special agent Chris Campion, lead federal investigator in the case, said Dugard's mother, Terry Probyn, was "ecstatic" her daughter was found.
"When I called her she was beside herself with joy, and I was present when she was reunited with Jaycee," he said. "It was a very emotional scene. Both of them were just overjoyed to be with each other again. There's going to be a period of adjustment, no doubt, but they're doing very well at this point. And the two daughters are probably as happy as Jaycee is to be part of this family, as well."
Police in Hayward, California, are trying to determine whether Garrido is linked to the 1988 kidnapping of Michaela Garecht, said Hayward police Lt. Chris Orrey.
Garecht and Dugard were of similar age and appearance, both were abducted in daylight, and a sketch of a suspect resembled Garrido, Orrey said. There are differences, as well, but she declined to elaborate.
The similarities in the cases, the fact that Dugard was found close to home and comments from neighbors make Murch think her daughter could have been on Garrido's compound.
"I understand that a few years ago, one of the neighbors called in and said that there were girls being kept in the backyard. ... She said that there were a number of girls that came and went, but that there was a core group of five," Murch said. She hopes her daughter was among them.
In Dublin, California, police were looking into whether Garrido was connected to the 1989 disappearance of Ilene Misheloff who was 13 when she was abducted, investigators said.
Garrido was convicted of kidnapping and raping Katie Callaway Hall in 1976. He was released after serving 10 years of a 50-year sentence. He was labeled a sex offender and put on lifetime parole.
Garrido abducted Hall after she agreed to give him a ride to a supermarket. He took her to a mini-warehouse in Reno, Nevada, where he raped her. She managed to escape soon afterward.
"I can't imagine what Jaycee is going through. He had me for eight hours. He had her for 18 years," Hall said.
During those years, according to Garrido's own writings, he began to feel remorse for things he had done.
The revelations came in documents obtained by CNN that Garrido delivered to an FBI office in San Francisco, California, just days before he was arrested in the Dugard case.
The writings were a two-part manifesto in which he discussed the "Origin of schizophrenia revealed." In the second part of the documents Garrido detailed his struggle with sexual urges in "Stepping into the light." He confessed his past aggressive sexual impulses, but said he is no longer that man. Watch interview with Garrido »
Garrido also wrote that he could control minds with sound and could help others before they committed violence.
Dugard apparently led an outwardly unremarkable life. Customers of Garrido's printing company, Printing for Less, knew her as "Allissa."
"She was always having a very pretty smile on the face," said Deepal Karunaratne, who had real estate brochures printed. "She comes and talks to me and was always smiling. She was a very pretty girl, a very pretty young lady."
Garrido even used a picture of Dugard to promote his printing company, customer Cheyvonne Molino said.
"About 10 years ago, when he started printing our cards, he was looking for business," said Molino, who runs an auto wrecking yard with her husband. "He would leave your cards with his cards and her picture -- blonde hair, blue eyes, beautiful young lady. She was on everyone's card."
Dugard's two daughters -- 11-year-old "Angel" and 15-year-old "Starlet" -- attended birthday parties and loved the TV show "Hannah Montana."
The media "made it seem like these little girls were living like wolves or jungle kids in the backyard dungeon. Perhaps that's it, but they didn't give that visual to me," Molino said.
Two weeks ago, the girls attended a birthday party for Molino's daughter.
"They were polite," Molino said. "They were well-mannered."
CNN's Ed Lavandera, Patrick Oppman, Paul Vercammen, Dan Simon and Mallory Simon contributed to this report.