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CARLSBAD, Calif. — Police arrested a man accused of sexually assaulting a teenage girl at a home in Carlsbad.

On Monday, a 16-year-old said she went to a home in the 3600 block of Carlsbad Boulevard to meet with a professional modeling photographer, according to Carlsbad police. The photographer, 52-year-old Robert Koester of Carlton, Oregon, was subcontracted by Carlsbad-based model management agency Frank.

The victim said during the photo shoot, Koester sexually assaulted her. She left the shoot and told her father. The next day, the girl and her father contacted Carlsbad police.

Police went to the home and arrested Koester. Investigators served a search warrant and found evidence related to the crime.

Investigators believe Koester worked with several clients and used the aliases Rhake Winter and Bert Kay. They have been working closely with the agency to identify other witnesses or victims.

Koester was booked into the Vista Detention Facility and charged with battery with great bodily injury, sexual battery, possession of child pornography and providing harmful material to a minor. Koester posted bail and was released until future court proceedings.

Anyone with information is asked to call police at 760-931-3819 or email