CONCORD, N.H. — More than 30 years ago, the bodies of a young woman and girl were found inside a steel barrel in the woods of Allenstown, N.H. Fifteen years later, the skeletal remains of two more little girls were found, just 100 yards away.

The victims were never identified, although DNA tests showed three of them were related. A family had seemingly disappeared without notice. Police were stumped.​

The murders remained unsolved — until now. In a stunning breakthrough, authorities here announced Thursday that a man named Bob Evans, who murdered his wife in California in 2002, had killed the four people, one of whom was his daughter.

He had also probably killed 23-year-old Denise Beaudin, his girlfriend who disappeared in 1981 with her baby daughter.

Beaudin was never found, but her baby survived, cared for by her captor for five years before being abandoned.

She was later adopted by a California couple, and went on to lead what appears to be a remarkably normal life, marrying, and having children of her own. But she remained curious about her past — and it was that curiosity that triggered a complex series of events that led to Thursday’s announcement.

In 2014, she submitted her DNA in an effort to find her biological parents, a quest that led to the discovery last summer that Beaudin was her mother.

California investigators alerted New Hampshire authorities to the connection, and Evans was later identified as the man who had abandoned Beaudin’s daughter under another name. In October, DNA evidence showed that Evans was the biological father of the unidentified 2- to 4-year-old whose body was found in Allenstown in 2000.

“We believe we have our killer,’’ Senior Assistant Attorney General Jeffrey Strelzin announced at a news conference Thursday, saying Evans used different aliases while crossing the country and had a history of abusing women and children. “He certainly fits the profile of a serial killer.’’

Investigators hope the revelation will help finally identify the victims found in Allenstown and locate Beaudin, and urged anyone with information to contact them. Evans, who authorities say probably used an alias, died in prison in 2010 under a different name.

Evans lived in New Hampshire from about 1977 to 1981 and worked as an electrician at Waumbec Mills in Manchester, authorities said. He also did electrical work at a store on a property that bordered Bear Brook State Park, where the barrels containing the bodies were later discovered. He sometimes used the property to dispose of material from the mill, authorities said.

In 1985, hunters stumbled upon a barrel containing the decomposing bodies of a woman, believed to be in her mid-20s, and a girl, probably 9 to 11. Fifteen years later, a State Police sergeant newly assigned to the case discovered the second barrel, which contained the skeletal remains of two more girls, one believed to be 3 or 4, and the other 2 or 3.

Beaudin has been ruled out as one of the victims. Investigators have determined that the woman is related to the oldest and youngest girl, but not to the middle child, who was Evans’s daughter. Investigators believe the four victims were killed at the same time, between the late 1970s and 1981.

Authorities said Evans may also have killed the mother of his daughter.

Strelzin said investigators believe Evans murdered Beaudin shortly after she was last seen by relatives in November 1981. Her relatives told authorities they never reported her missing because they believed the couple disappeared because they were having financial difficulties.

Officials said they do not know why Evans decided to keep Beaudin’s daughter, whom he called Lisa, alive for years, during which he may have been the primary caretaker for the child. Lisa has told officials she has “shadowy’’ memories of a woman being part of her youth, authorities said.

Strelzin speculated that Evans may have used the child as “bait,’’ to attract other women with children.

“He had a reason for keeping Lisa with him, and then he didn’t want her anymore,’’ Strelzin said.

In June 1986, while Evans was living and working at the Holiday Host trailer park in Scotts Valley, Calif., passing himself off as Gordon Jenson, he abandoned Beaudin’s daughter, leaving her with another family he knew at the trailer park, authorities said.

She was later placed in foster care, adopted, and raised by a loving family, Strelzin said.

Evans was later convicted of abandoning the child and sentenced to three years in prison. He was paroled in 1990 and immediately disappeared, according to authorities.

Now a mother with three children of her own, Beaudin’s daughter provided a DNA profile to an adoption website, which worked with the San Bernardino County Sheriff’s Office to identify her.

After discovering the woman’s identity, the sheriff’s office alerted New Hampshire State Police and the Manchester Police Department, ultimately leading to the discovery that Evans was linked to the Allenstown victims.

In a statement read at the news conference, Lisa described herself as “a victim in this incredulous story,’’ and asked for privacy.

“I have three beautiful children and a loving husband,’’ she said. “I presently have a happy and secure life (that I want) to remain intact.’’

Lisa said she had been reunited with her grandfather and cousins and thanked “all the organizations and tireless individuals who made this possible.’’

In 2001, Evans, then using the name Lawrence Vanner, married his girlfriend, Eunsoon Jun, in a backyard ceremony in Richmond, Calif., and moved into her home. The following year, she disappeared. Police discovered her murdered and dismembered body covered underneath mounds of kitty litter in the basement.

After he was fingerprinted, authorities discovered that Vanner had previously served time as Curtis Mayo Kimball.

He pleaded guilty and was serving a life sentence in a California prison when he died of natural causes, officials said. It’s not clear how old he was, but he was likely in his late 60s.

Investigators recently searched the Manchester home where Beaudin had lived with Evans, but found no evidence of human remains. They said they plan to conduct further searches of the Allenstown property where the other victims were found.

Evans was an alcoholic, who stole people’s identities and told countless stories about his past, claiming he was born in Wyoming and Texas, and that his wife was murdered in Corpus Christi, according to authorities.

“He was a calculating guy,’’ Strelzin said. “He didn’t give out much information about himself. He was being smart about trying to cover his tracks.’’

Investigators said that Evans is also an alias, and that they do not know what his real name was. They think he might have served in the military, possibly the Navy, in the 1970s, but do not know where he was born or raised before he arrived in New Hampshire in the 1970s.

“This is a guy who is a chameleon,’’ Strelzin said. “We are all real confident that his real name is not Bob Evans. We don’t know how much of a life he had before he showed up in Manchester.’’

When Evans was arrested by Manchester police in 1980 for writing a bad check and stealing electricity, he listed his spouse as Elizabeth. That woman has never been located.

Shelley Murphy can be reached at shmurphy@globe.com. Follow her on Twitter @shelleymurph. John R. Ellement can be reached at ellement@globe.com. Follow him on Twitter @JREbosglobe.