SAN ANTONIO -

A registered sex offender was arrested on Sunday at a youth cheerleading competition at the Alamodome after he was caught videotaping competitors.

Andrew Sanchez III, 60, is charged with improper photography.

"Some of the adults who were at the competition flagged down an officer. Apparently, they had seen this subject and became suspicious of him," San Antonio police Sgt. Javier Salazar said.

The off-duty officer went behind Sanchez and saw him videotaping competitors at the American Cheer Power Southern National Championship, and zooming in on the pelvic area of young girls.

The officer questioned Sanchez and determined he had no children at the event and was there alone.

Sanchez was arrested and booked in the Bexar County Jail.

"He was questioned by Special Victims Unit detectives who did obtain a search warrant for the contents of his camera, and did find evidence on there that led to the charge of improper photography," Salazar said.

A representative for American Cheer Power said nothing like this has ever happened before at one of its competitions.

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