Anthony Cantu, 19, is accused of having a year-long sexual relationship with a 13 year old runaway.
San Antonio police arrested Cantu late Monday night after the girl's parents found them in a Northwest Side motel.
Police said the teen confessed to her parents that she had been having sex with Cantu for about a year, since she was 12-years-old.
The girl told detectives she met him on the internet site, "Mocospace," but told him she was 14.
Police said the parents found their daughter with Cantu at a motel in the 7700 block of Louis Pasteur Drive.
Cantu was due to appear before a magistrate Tuesday morning. It was still unclear what charges he face.
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