MODESTO (CBS13) — A heinous assault on a 62-year-old woman has led Modesto police to make an arrest in what they describe as a “needle in a haystack investigation.”

The woman was beaten unconscious in a mini-mall parking lot overnight and wasn’t discovered until Thursday morning.

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Police had few leads, with the exception of video camera surveillance showing the brutal attack. 

Moments before the attack on the woman, the video shows a man walking into frame, turning his head looking to see if anyone is watching.

He confronts the woman, and lunges at her, then beats her with his fists even as she lays on the ground.

“We needed to get this person off off the streets, to prevent any further random attacks,” Modesto Police Department Sergeant Kalani Souza said. 

Modesto police say the attack was so violent and unprovoked, a sergeant with the violent crimes unit assigned every detective on the force to search the streets for this suspect, using only the video of the attack as a lead. 

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“He actually pulled all of his team, off of whatever they were working on at the time, and also our major crimes unit, which is our newly formed undercover unit, to come in and help find this person, and get him off of the streets,” Sergeant Souza said. 

One of the investigators identified the suspect within 12 hours of the search at the Modesto transit station. 

“You know in our city of 212,000 people they were able to find him,” Souza said.

Police say the man caught on camera beating the woman in the video is now booked in jail. He has been identified as 21-year-old Alexander Knab.

Investigators say Knab confessed to the crime.

A brutal beating led police to go all out in what they describe as “a needle in a haystack case” that’s now cracked.

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Modesto police say they still haven’t been able to interview the victim in this case, and they won’t try to until she is further along in her recovery.