MILWAUKIE -- Police are crediting a Portland man for helping to capture a registered sex offender who dressed as a woman and slipped into the girl's dressing room at a swim park last week.

The sex offender, Thomas Lee Benson, 39, of Gresham has been charged with unlawful contact with a child, unlawfully frequenting a place where children congregate and unlawful entry into a motor vehicle. He is being held in the Clackamas County Jail, with bail set at $100,000.

This isn't the first time Benson has been charged with improper contact with children. Benson's record includes convictions for first-degree trespassing and first-degree sexual abuse involving three girls, who were 5, 7 and 8 years old when the crimes took place. In 2007, he dressed as a woman to enter a dressing room at Portland's Mt. Scott Community Center, where children were changing into swimsuits.

Detective Jim Strovink, Clackamas

spokesman, said Benson was seen roaming around the

, 7300 S.E. Harmony Road, east of Milwaukie last Friday afternoon, engaging children in conversations.

At the same time, Tayo G. Cotton, 26, of Portland was supervising a large group of children he had taken on a field trip to the aquatic park. After hearing giggles coming from the girl's locker room, he saw a suspicious person leave the room. Cotton then tried to stop the person, who walked away -- then ran.

Cotton followed the person through a nearby Sears department store, giving chase through the parking lot on the north side of the complex. The person then tried to open several car doors to evade capture, Strovink said.

The fleeing person eventually targeted a car driving slowly through the parking lot with an open rear window, then reached in an opened the car door.

That's when Cotton grabbed the suspect and pulled him from the car. A Clackamas County sheriff's deputy arrived and handcuffed Benson, who was wearing a bra, lipstick and eye-liner.

"Had it not been for all the conscientious and valiant efforts provided by Tayo G. Cotton, the suspect involved may not have been successfully apprehended," Strovink said.

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