A Denver-area doctor accused of uploading scores of images of child pornography admitted to “surreptitiously videotaping” naked boys during medical exams, according to federal court documents made public Wednesday.

The U.S. Attorney’s Office has charged Dr. Justin Bowen Neisler, 31, with transportation of child pornography following his arrest on March 13. He was accused of uploading sexually explicit videos and photos of children onto a social media platform.

Some of the images include depictions of sex involving adults and children, according to court documents.

The new disclosures came in a ruling denying Neisler release from custody.

RELATED: Denver-area doctor busted, facing child porn charges after search of apartment

“The defendant, a doctor, admitted to surreptitiously videotaping naked males as young as eleven years old during physical examinations,” federal Magistrate Judge Scott T. Varholak wrote. “…  a review of these videos reflected that the defendant appeared to gain sexual gratification from the examinations.”

Neisler was fired from his position as a resident at St. Anthony Family Medicine – 84th, located at 2551 W. 84th Ave., in Westminster, following his arrest.

In a statement, Centura Health spokeswoman Wendy Forbes, said St. Anthony’s officials were “deeply disturbed and saddened that one of our former physicians … has been charged with crimes related to transportation of child pornography.”

The investigation is ongoing and potentially includes “other federal criminal child exploitation offenses, including the production of child pornography,” according to a news release from the U.S. Attorney’s Office in Colorado.

When investigators raided his Denver apartment earlier this month, they took multiple computer storage devices and several cameras, according to court documents. Investigators also took a "spy pen camera instruction manual," court documents say.

Colorado Department of Regulatory Agency records show that Neisler has a current state medical license. According to Georgia Composite Medical Board records, he also is licensed there.

According to a search warrant obtained by 9Wants to Know, the investigation began in October when officials at Tumblr, a blogging and photo-sharing website, reported to the National Center for Missing and Exploited Children that a subscriber had “uploaded sexually explicit videos and/or images of children onto a webpage.”

That tip also provided investigators with an e-mail address linked to the subscriber.

More tips came in the following months. One on Nov. 2 to Colorado Springs police reported “32 images and/or videos of child pornography” had been uploaded by a user with the same e-mail address, according to the warrant.

By early January, according to the document, investigators had identified Neisler as the subscriber with that e-mail address.

In the search of Neisler’s Denver apartment, FBI agents took computer hard drives, data cards, and cameras.

Contact 9NEWS reporter Kevin Vaughan with tips about this or any story: kevin.vaughan@9news.com or 303-871-1862.

SUBMIT TIPS: Anyone with information relevant to the investigation was asked to contact the FBI at denvermd@fbi.gov or call 303-629-7171, ext. 1

SUGGESTED VIDEOS | Investigations from 9Wants to Know