SHERMAN, Texas (CBSDFW.COM) – A North Texas man was sentenced for child pornography violations in federal court on Friday.

Richard Denver Belden, 41, pleaded guilty last June to receipt and possession of child pornography and was sentenced to 35 years in federal prison by U.S. District Judge Amos Mazzant.

According to information presented in court, in May 2018, a Plano Police detective was conducting an undercover investigation into Internet programs know for trading child pornography and located a user, later identified as Belden, who was making a large quantity of child pornography available for download.

Over the course of two days, the detective downloaded over 4,000 images and videos of child pornography from Belden.

Members of the Collin County Sheriff’s Office obtained a search warrant for Belden’s apartment, in Allen, Texas and on May 15, 2018, the Sheriff’s Office and Plano Police Department executed the search warrant.

Upon entering the residence, they discovered Belden actively downloading and distributing child pornography on a laptop computer. In addition to the laptop, Belden owned a tower containing 15 hard drives, totaling 57 TB of storage.

The Plano Police Department and FBI child exploitation task force spent months forensically analyzing Belden’s digital media. Officers located thousands of images and videos of child pornography, including depictions of children as young as toddlers and depictions of sadistic or masochistic abuse. Belden was indicted by a federal grand jury in June 2018.

During the sentencing hearing, a Plano Police Department Detective testified about the undercover investigation, the forensic review of Belden’s devices, and the content of those devices. Belden’s sentencing guidelines included a term of imprisonment of 210 to 262 months. The government requested that the Judge vary upward and impose a sentence of 420 months. Based on Belden’s history and characteristics and the nature and circumstances of his offense, Judge Mazzant granted the government’s motion and sentenced Belden to a total term of 420 months (35 years) imprisonment, to be followed by 20 years of supervised release.

“These type of cases show the real depravity of parts of our society,” said U.S. Attorney Joseph D. Brown. “We are fortunate that law enforcement is out there looking for these people.”

“Today’s result is the product of the outstanding collaboration between the FBI and its local partners,” said FBI Special Agent in Charge Matthew J. DeSarno. “The FBI, through the North Texas Child Exploitation and Human Trafficking Task Force, will continue to work tirelessly to keep our kids safe. This lengthy sentence will hopefully serve as a warning for all those who would seek to prey on the most vulnerable among us.”