Stonington pediatrician Todd Parrilla pleaded guilty this morning to receiving and distributing child pornography.

He faces a mandatory minimum of five years in prison and a maximum of 20 years when he is sentenced in October. The government is expected to ask for a reduction in his recommended 210- to 240-month sentence because he has admitted responsibility and has agreed to cooperate with the Federal Bureau of Investigation should agents ask for his help with future child pornography investigations. He will be required to register as a sex offender with the state and federal government upon his release.

Parrilla, 48, was part of the thriving Westone pediatrics practice in Stonington. He initially took a leave of absence from the practice when arrested in August 2011, then resigned.

He has been free on bond under home confinement and on electronic surveillance while his case was pending and will remain free until he is sentenced on Oct. 24.

According to the government, Parrilla had more than 100,000 images of child porn and 10,000 videos on his computers. A forensic analysis determined some of the images were sadistic and masochistic.

Parrilla stood before Judge Vanessa L. Bryant and admitted his guilt as his parents looked on from the gallery in U.S. District Court in Hartford. Though he has retained his medical license, the judge explained that his guilty plea meant that it is unlikely he will ever practice pediatric medicine again.

The office U.S. Attorney David B. Fein issued a press release following the proceeding.

"This defendant possessed and distributed tens of thousands of images and videos portraying the sexual abuse of children," said Fein. "This is a heinous crime. That it was committed by a pediatrician, whose profession is committed to the well-being of children, makes it especially disturbing. I commend the FBI and the Connecticut Computer Crimes Task Force for investigating this matter, and the tireless work they do every day to investigate these crimes and protect children from exploitation."

Parrilla came to the authorities' attention in July 2011, when a law enforcement officer in Kansas City, Mo., acting in an undercover capacity, logged into a publicly available Internet file-sharing program and downloaded 104 images of child pornography from a shared directory maintained by Parrilla.

On Aug. 23, 2011, Parrilla was arrested following the execution of a search and seizure warrant at his residence. On that date, the FBI seized two computers, three detachable hard drives, computer-related components and numerous printed images of child pornography.