A former Island resident and licensed therapist has pleaded not guilty to accusations of misconduct after being caught unclothed with a 15-year-old boy at his home earlier this year.

According to documents released by the King County Prosecutor’s Office, Thomas Arthur Gill, 63, a recent resident of Mercer Island, has been charged with one count each of indecent liberties and communication with a minor for immoral purposes. Gill was arraigned last week and pleaded not guilty. Gill’s social worker license was suspended from the state Board of Health. The defendant is out of jail on $15,000 bail. Gill sold his family’s Island home, where the majority of the misconduct is suspected to have taken place, just two days before the incident occurred, county property records show.

The victim, who was diagnosed with autism, is a resident of Shoreline. Gill was the boy’s therapist and had occasionally counseled the teenager at his former Island home, located near the high school. Gill was counseling the victim through the Attachment Center Northwest in Kirkland, a firm specializing in treating youth with attachment and trauma-related issues.

According to an investigation led by Island police detective Art Munoz, the defendant’s son had gone to see his father at the Island home on Saturday, May 10, went into his father’s bedroom and discovered the pair without any clothes on, according to court documents. Both of Gill’s sons are graduates of Mercer Island High School.

Police and Child Protective Services were notified of the incident after the victim mentioned it to an educator in his Shoreline Crest High School classroom.

During interviews with Munoz, the victim told police that he had also been unclothed and discussed sex during numerous therapy sessions at Gill’s former Mercer Island home. Inappropriate touching that occurred at Gill’s home was documented in the investigation as well.

Munoz also interviewed the victim’s mother, who told the detective that her son had been seeing Gill weekly for therapy for three years. She was notified of the incident by another doctor treating her son.

Court documents reveal there are other potential victims who need to be identified and interviewed. Munoz said there were no new leads or victims identified at this point, but the investigation was ongoing. A case-setting court hearing will take place on July 10.