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Armed with DNA and a family tree, police arrested a Colorado man in connection to the 1973 slaying of a Southern California girl, authorities said Wednesday.

James Alan Neal, 72, was picked up in Colorado Springs on Tuesday and charged with the murder of 11-year-old Linda O'Keefe, Newport Beach police and Orange County prosecutors said.

Neal became a suspect in the slaying through "genealogical DNA," Orange County District Attorney Todd Spitzer said.

"The hit on the genealogical DNA ... came back and hit in January so it was very recent," Spitzer said.

Even after detectives got the lead through genealogical DNA, investigators needed to a secure a sample from Neal, Spitzer said.

Police and prosecutors on Wednesday said they put Neal under surveillance and eventually got his DNA — though they did not detail exactly how.

Spitzer lauded noted DNA investigator CeCe Moore for helping police develop a "pointer" toward Neal. The DNA researcher Moore has been on the forefront of linking cold cases to suspects through genetic material voluntarily offered by Americans doing ancestry research.

Linda O'Keefe was last seen alive in Corona Del Mar, California, in July 1973. Newport Beach Police Department

Neal moved to Southern California from Chicago before the murder and relocated to Florida after the girl's slaying, authorities said.

At the time of the murder, Neal was using the name James Allen George Layton, prosecutors said. He later changed his name, officials said.

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"He lived here in the 1970s," Spitzer said. "He has a connection to Southern California."

Neal has been charged with one count of murder — with the special circumstances of kidnapping and committing lewd and lascivious acts upon a child younger than 14, Spitzer said.

He is being held in Colorado, and if he waives extradition, could be moved to California before the end of the week, officials said.

Prosecutors are considering seeking the death penalty against Neal. But Spitzer admitted that it is a murky legal decision because capital punishment was not an option when the 11-year-old was killed.

At the least, prosecutors will ask for life without the possibility of parole if Neal is convicted, the district attorney said.

Police also want to know if Neal could be linked to other crimes.

"Individuals who engage in sexual activity against minors tend to ...have certain indicators of a predatory nature," Spitzer said. "I want to know if there are any other victims."

O'Keefe's parents have since died, but police said they keep her two surviving sisters updated on the investigation.

Newport Beach police said last year they were taking a fresh look at the slaying of Linda O'Keefe, who lived in the Corona del Mar neighborhood and was last seen alive July 6, 1973, as she walked home from summer school.

The girl, whose body was found the next day, was strangled.

“Linda was last seen talking to a stranger in a van,” Newport Beach Police Chief Jon Lewis said Wednesday. “Linda never made it home that afternoon.”

“For 45 years, the Newport Beach Police Department continued to search for Linda’s killer," Lewis said. "Generations of investigators worked on her case. We never gave up."

Police and prosecutors in Southern California thanked the FBI, the Colorado Springs Police Department and the El Paso County Sheriff’s Department in Colorado for their assistance.

Newport Beach police in July released a sketch of a man, the possible suspect, based on DNA collected at the scene.

A poster of James Alan Neal during the Newport Beach police and Orange County prosecutors news conference on Feb. 20, 2019. KNBC

"We have heard from a number of her friends from when she was in school, and her death has touched so many people," Newport Beach police spokeswoman Jennifer Manzella said at the time. "They haven't forgotten about her and we haven't, either."

Police also urged the public to share details about O'Keefe's disappearance on social media with the hashtag #Lindastory.

"The tweets extend the period of time that Linda's story can be out there for people to relate to," Manzella said in July. "We want as many sets of eyes on that sketch as possible, so somebody can recognize the face of a killer so we can get justice."