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Denver D.A. Praises 'Katie's Law' In Arrest Of Serial Rape Suspect

DENVER (CBS4) - He got into a fight in a grocery store parking lot and now Denver police believe DNA evidence connects that man to three rapes -- one involving a 13-year-old girl.

The first assault was in 2008 and the most recent was last year. Police say in two of the rapes the attacker told the victims he was a police officer.

Police have not released the mug shot of William Costello, 47, while they conduct witness lineups.

The most recent assault happened to a woman who was waiting at a bus stop last September. She says a man pulled over, told her he was a police officer and ordered her to get inside his car.

A physical fight with an elderly man in a King Soopers parking lot netted Costello a felony assault charge in July of this year. From there Katie's Law and his DNA linked him to three other crimes.

"Here in Denver, this is one of the most significant offenses that we've had," Denver District Attorney Mitch Morrissey said.

SERIAL RAPE ARREST
(credit: CBS)

Passed in 2010, Katie's Law allows DNA to be collected after a felony arrest and charge. The DNA can then be compared against a criminal DNA database even if there is no felony conviction.

"Three unsolved sex assaults out of Denver came up as a match to his DNA," Morrissey said.

The first case in 2008 involved a 13-year-old runaway who police believe Costello picked up near 16th and Bellaire. According to court documents, the girl says there was a 2-year-old boy in the backseat while she was raped.

The second case is from 2010. A 22-year-old woman claims she wanted a ride through a fast food drive-through near Colfax and Krameria and climbed in to a car with a stranger. Instead of taking her to the restaurant, the woman says she was raped in the back seat by a man who claimed he was a police officer.

The final case was in 2011. A woman waiting for a bus near 32nd and Federal says she was ordered to get in to a car by a man with a gun also claiming he was law enforcement. She too was raped inside the car.

Morrissey says without Katie's Law the cases may have gone unsolved.

"To see it actually have an impact on this type of case, it's very, very important to us," he said.

Costello was expected to make his first court appearance Tuesday morning. He's being held on a $200,000 bond.

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