Get breaking news alerts and special reports. The news and stories that matter, delivered weekday mornings.

BELLEFONTE, Pa. — A son of former Penn State University assistant football coach Jerry Sandusky pleaded guilty Friday to charges he pressured a teenage girl to send him naked photos and asked her teen sister to give him oral sex.

Jeffrey Sandusky's plea deal comes a week before his trial was slated to begin on the charges, and nearly six years after his father was arrested in a child molestation case that shook Penn State and is still working its way through criminal and civil courts.

Jeffrey Sandusky pleaded guilty to all 14 counts, including solicitation of statutory sexual assault and solicitation of involuntary deviate sexual intercourse.

A call seeking comment from his lawyer wasn't immediately returned Friday.

This undated file photo provided by the Centre County Correctional Facility shows Jeffrey Sandusky. Jeffrey Sandusky, the son of former Penn State University assistant coach Jerry Sandusky has pleaded guilty pressuring a teenage girl to send him naked photos and asking her teen sister to give him oral sex, Friday, Sept. 15, 2017. Centre County Correctional Facility / AP file

As part of the deal, 41-year-old Sandusky will spend up to six years in state prison, but the judge could impose as much as eight years.

Let our news meet your inbox. The news and stories that matters, delivered weekday mornings. This site is protected by recaptcha

Centre County District Attorney Stacy Parks Miller said the plea deal ensures the victims don't suffer additional trauma by testifying at the trial.

"We are happy that these girls can move forward and experience a life with adults that deserve their trust," she said.

One of six adopted children of Jerry Sandusky, Jeffrey Sandusky has been a stalwart supporter of his father, who is serving a lengthy prison sentence for sexual abuse of 10 boys.

He regularly attended his father's court proceedings alongside his mother, Dottie Sandusky, who also has consistently supported her husband and fought to clear his name.

Jeffrey Sandusky, a state prison guard, knew the girls through their mother, authorities said.

A state trooper said in the arrest affidavit that last November, their father turned over to investigators text messages from Sandusky in which he asked one of the girls for nude photographs.

The affidavit said Sandusky told the teen in texts from March 2016 that "it's not weird because he studied medicine" and instructed her "to not show these texts to anyone."

The girl's mother told investigators that when she confronted Sandusky, he told her "he knows it was wrong and inappropriate," police said.

The girl told police the texts made her uncomfortable and that "he kept pressuring me and asked me multiple times not to show the texts to anyone," police said.

Prosecutors allege Jeffrey Sandusky sought oral sex from the other girl in 2013. She was 15 years old at the time.

That teen told investigators that Jeffrey Sandusky told her later: "I can't even say anything except I'm sorry."