MADRAS — A Terrebonne man pleaded guilty to sexually abusing children and uploading hundreds of child sexual abuse images on the internet over a span of roughly four years.

Ronald Dean Jarchow, 67, was sentenced on Sept. 22 to more than 36 years in prison. He pleaded guilty to first-degree sexual abuse, encouraging child abuse, second-degree unlawful sexual penetration and using a child in a display of sexually explicit conduct, according to Jefferson County District Attorney Steve Leriche.

The National Center for Missing and Exploited Children reported to law enforcement investigators that Jarchow uploaded 248 images of child sexual abuse to his Yahoo! account between January 2017 and July 2021, Leriche said.

Jarchow digitally added the faces of children he knew onto these images and “engaged in hands-on sexual abuse of more than one child victim as well,” Leriche said.

Elijah Michalowski, a senior assistant attorney general for the Oregon Department of Justice, said during a sentencing hearing that, with these images, Jarchow had harmed four child victims that authorities knew about, and “countless” others they didn’t.

Two of these victims spoke in court and asked that Jarchow remain in prison for the rest of his life.

Jarchow’s attorney, Thaddeus Betz, argued that Jarchow should be given a lesser sentence — 100 months — than what was requested by prosecutors — 1,285 months. Betz declined to comment.

Jefferson County Circuit Court Presiding Judge Annette Hillman gave him 440 months, calling him “the definition of a sexual predator,” according to Leriche.

In a statement, Leriche said: “The Jefferson County District Attorney’s Office would like to commend the courage of the victims in disclosing their abuse at the hands of (Jarchow) and would like to express its deepest gratitude to the Oregon Department of Justice for their willingness to take on this important case.”