A 45-year-old Mountain View man was sentenced Wednesday to 40 years in prison for sexually assaulting two minors between February and May 2025.

Hilo Circuit Judge Peter Kubota sentenced Joseph Donald Tibbs to 20 years in prison for one victim and 20 years for the second victim.

After hearing arguments from both the prosecution and defense, the judge sentenced Tibbs to a 40-year prison term by ordering that the sentences imposed be served consecutively.

In addition, Tibbs — who declined an opportunity to address the court during sentencing — will be required to register as a sex offender.

Tibbs pleaded guilty on July 21, 2025, to four counts of first-degree sexual assault and two counts of first-degree promotion of child abuse. In return for his guilty pleas, prosecutors dropped 11 other charges, including four additional counts of first-degree assault and two counts of incest.

According to court documents, Person 1 and Person 2 — the female victims of Tibbs — were at least 14 years old but less than 16 and are related to Tibbs by blood.

Tibbs produced or participated in making child pornography with photos or videos of Persons 1 and 2. He also disseminated child pornography and possessed 30 or more images of child pornography, with at least one image containing a minor younger than 12.

The charges against Tibbs stemmed from a monthslong investigation involving the Internet Crimes Against Children Task Force, Hawaii Police Department, the Hawaii County Office of the Prosecuting Attorney, and Homeland Security Investigations.

“It is my hope that (Wednesday’s) sentencing sends a powerful message to those who betray family trust and prey upon our keiki, that they too will be held accountable for their actions,” Prosecuting Attorney Kelden Waltjen said in a statement. “… Through strong collaboration and shared investment into protecting our community, we will continue to prioritize the identification, investigation and prosecution of those who sexually abuse and exploit children.”

Email John Burnett at john.burnett@hawaiitribune-herald.com.