MCMINNVILLE, Ore. — A suspected sexual predator has been indicted and charged in connection with sexual assault crimes against multiple victims in Oregon and California, according to the FBI.

Robert Koester, 52, was arrested in Carlsbad, California in November 2018. He remains in custody in San Diego.

Alleged victims have been identified across the United States, and the FBI and local law enforcement agencies are asking the public to help identify additional potential victims.

Also known as Bert Kay, Rhake Winter and Qitooly, Koester was a professional photographer who took nude photos of models. He is alleged to have sexually assaulted many of the models, including some younger than 18.

Police believe Koester, who owns a farm in the rural Yamhill County town of Carlton, Oregon, has potentially been committing sexual assault crimes since 1994.

Yamhill County District Attorney Brad Berry said there are four known victims in Oregon and they suspect there are "many more."

Koester has been charged by a Yamhill County grand jury with 32 felony counts of sexual abuse against the four victims, including first-degree rape, first-degree sodomy, and first-degree unlawful sexual penetration. He is also charged with causing another person to ingest a controlled substance.

One of the victims was a minor, police said.

Koester currently faces 25 felony charges in southern California, including child sexual abuse, production of child pornography, and sexual exploitation of a minor.

If you or someone you know is a victim of Koester, the FBI asks that you complete this secure, confidential form. You can also submit information via email to modelcase@fbi.gov. For more information, visit fbi.gov/modelcase.

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Additional resources provided by the FBI

FBI Help for Victims Brochure

Caring for Kids: What Parents Need to Know About Sexual Abuse

Adult Survivors of Childhood Sexual Abuse

Suicide Prevention Lifeline

American Psychological Association resources on sexual abuse

Rape, Abuse, & Incest National Network (RAINN)

National Center for Victims of Crime