A Denver doctor arrested as a suspect in a child pornography case videotaped naked boys, as young as age 11, during physical exams, according to court documents.

Dr. Justin Bowen Neisler, 31, who formerly practiced at St. Anthony North Family Medicine – 84th clinic in Westminster, “admitted to surreptitiously” videotaping the children who were in his care, according to an order of detention filing dated Tuesday.

Neisler was arrested by FBI agents on March 13 on suspicion of knowingly transporting child pornography in interstate commerce. He allegedly repeatedly posted child porn to Tumblr accounts.

After serving a search warrant at Neisler’s Denver residence, investigators interviewed him and the videotaping revelations surfaced.

“According to the agent, a review of these videos reflected that the defendant appeared to gain sexual gratification from the examinations,” the court document said.

A news release from the U.S. Attorney’s Office in Colorado on Tuesday afternoon said Neisler would remain in custody until further court proceedings.

Federal prosecutors expect to file additional charges in the case. They also believe that Neisler would be a flight risk if free, according to the document.

The hospital fired Neisler, who worked there for less than nine months, from its family residency program after finding out about his arrest, according to a statement from Centura Health.

Neisler has been licensed to practice medicine in Colorado and Georgia since 2016 and was affiliated with Centura Health and HCA-HealthONE networks, according to the U.S. Attorney’s Office news release. Neisler’s Colorado medical license was active, according to the state Department of Regulatory Agencies database.

On Wednesday investigators encouraged anyone with pertinent information on the case, or on the suspect, to call the FBI at 303-629-7171, ext. 1; or send an email to DENVERMD@FBI.GOV.