SAN DIEGO -- Kenneth Banks says he is not guilty of kidnapping and molesting a 12-year-old girl.

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More 'Cold' Cases May Be Solved

But prosecutors say DNA evidence will prove that he did.

The City Heights man has said through an attorney that he doesn't dispute the encounter, but says he thought he was picking up a prostitute.

For her part, the 12-year-old girl says she does not remember her attacker. It happened more than a year ago, it was dark, and the girl was gripped with fear.

"This case went unsolved for almost 18 months, until we were able to connect saliva. And that is they key to solving this crime," prosecutor Jennifer Gianera said.

Prosecutors say they are confident that Banks is their man, and the case is an example of how DNA evidence is changing the face of crime prevention. And in San Diego, crime experts say a lot of thanks goes to the state data bank.

"We can track crimes that we didn't necessarily know were linked to each other with the database, as well as track criminals across the state and across the country, by the genetic evidence they're leaving behind," criminologist Connie Milton said.

DNA evidence has recently helped crack one of San Diego's most notorious unsolved murders -- allegedly linking the deaths of two South Bay boys to Scott Thomas Erskine, eight years after the boys were killed.

"The statistical analysis gives you numbers that are millions and billions and trillions greater than the actual population of earth," Milton said. "And in my scientific opinion that is an identity."