Linda Ann O'Keefe's killing in 1973 in Newport Beach, California went unsolved for more than four decades

On the day Linda Ann O'Keefe died, it was a cooler-than-normal July morning in Newport Beach, California. The brown-haired, blue-eyed 11-year-old got a ride to summer school - about half a mile away - but had to walk home in the afternoon.

It was July 6, 1973, a Friday. When O'Keefe didn't return home right away, there was little concern at first. But when night fell and her whereabouts were still unknown, her parents called police and desperately combed the neighborhood, to no avail.

Investigators would later learn that the girl had last been seen at an intersection, talking to a stranger in a turquoise van. The following morning, O'Keefe's body was found in a ditch. She had been strangled and was still wearing a blue-and-white floral print dress that her mother had sewn for her.

Her death would go unsolved for more than four decades.

On Tuesday, nearly 46 years after O'Keefe's life ended, authorities arrested a man they say is suspected of being her killer: a 72-year-old living in Colorado named James Neal.

Police were tight-lipped about exactly how they solved the case but said they received a lead in January that prompted them to begin investigating Neal, who had been living in Orange County at the time of O'Keefe's killing but had since moved to Colorado.

Through surveillance, a sample of Neal's DNA was obtained - one that ultimately matched a sample taken from O'Keefe's body in 1973. Neal was arrested Tuesday "without incident" in Colorado Springs, Newport Beach Police Chief Jon Lewis said at a news conference Wednesday.

The arrest seemed to signal an end to an infamous cold case that had both haunted and motivated "generations of investigators" at the Newport Beach Police Department, Lewis said.

"Linda's face and her memory has been with us since the day this happened," he said. "Her picture hangs in our detective division, where our folks see it every day as a reminder of her and why we continue to pursue these cases."

Both of O'Keefe's parents have since died, but the girl was survived by two sisters, whom police had contacted with updates about Neal's arrest.

"As you can imagine, this was difficult news to receive," Lewis said. "It is bittersweet to hear that, yes, this case has been resolved. But again, it's a reminder of what happened. It was a difficult conversation . . . for me personally. On one hand, we were grateful that we could have that conversation and provide some closure."

Orange County District Attorney Todd Spitzer also called the arrest "bittersweet," noting that he had been 12 years old when the 11-year-old was killed. But he praised Newport Beach police for persisting through the decades.

Spitzer said a DNA sample was recovered from O'Keefe after her body was found and uploaded to a database, where it never matched others.

"That sample remained in the system for a long period of time," Spitzer said.

James Neal had been living in California at the time of the girl's murder but had since moved to Colorado

Spitzer refused to elaborate on how they were able to track down Neal and identify him as a suspect after 45 years, but he said police had received a "pointer notification through genealogical DNA" - perhaps suggesting that authorities had come upon DNA from someone related to Neal that would have implicated him as a possible match.

That DNA "hit" came in January, Spitzer said. After following and obtaining a DNA sample from Neal himself, police were confident enough to make an arrest, he added.

Spitzer also refused to confirm whether Neal had family members or children, saying the matter was under investigation.

"My office will never forget about cold cases," Spitzer said in a statement. "Our hearts go out to the victim and the victim's family in this case, having to endure decades without answers. We will make sure that the defendant is fairly and justly held accountable in a court of law."

In July, on the 45th anniversary of O'Keefe's death, the Newport Beach Police Department "live-tweeted" Linda's story - in her voice, from the perspective of her last day - in the hope of raising awareness about her cold case and shaking forth any new clues about her killer.

Police hoped that retelling the girl's story through the modern-day medium would help people from a different generation form an emotional attachment to the case. Using details from the investigator's decades-old case files, police relayed O'Keefe's last hours, as well as her family's frantic search for her, as if they were unfolding in real time, as The Washington Post's Meagan Flynn reported:

"At 6:42 p.m., six hours since her mother had last heard from her, O'Keefe's parents reported her missing to the Newport Beach Police Department, convinced by then O'Keefe was not simply running off with friends to retaliate for not getting a ride. Helicopters, police Jeeps and search parties scoured the area looking for signs of O'Keefe. Only one person, a woman who did not know anything about a missing girl, was close enough to hear her, and by then it was too late.

In July 1973, 11-year-old Linda Ann O'Keefe was murdered. In July 2018, her story touched millions of people through #LindasStory (https://t.co/yxv1fLFIZp). Today, we have a new message to share, and we are giving Linda a voice once more. — Newport Beach Police (@NewportBeachPD) February 20, 2019

"Just before midnight, 'a lady in the bluffs above Back Bay hears a female voice outside, screaming "Stop, you're hurting me," ' the police tweeted in O'Keefe's name. 'She listens, but hears nothing more. She doesn't know that I'm missing. That I'll be dead by morning. That I'll be found a couple hundred yards from her home.'

" As 'Linda' noted in the tweets in July, her case would generate numerous theories and a sketch of a 'person of interest' but ultimately grow cold."

Until 46 years later.

"Technology has caught up with the law," Spitzer said Wednesday.

Spitzer noted that the DNA lead police had obtained was wholly unrelated to the department's live-tweeting of O'Keefe's last day but said the exercise had served to revive the case in the public's mind.

"It didn't necessarily lead to the identification (of the suspect)," he said. "But it created an awareness . . . and opened doors for us to have this case pursued with renewed effort."