U.S. District Judge David Ezra sentenced a 67-year-old Hilo bookkeeper to 25 years in federal prison for receiving and possessing what the National Center for Missing and Exploited Children has called "the largest personal collection of child pornography that it had ever received," the U.S. Attorney’s Office said.

Federal law enforcement agents recovered from Ronald Felts’ Hilo home two computers and eight external hard drives containing about 1.7 million pornographic images and about 31,000 pornographic videos of children. The agents then turned over the material to the national center.

Felts bought access to various websites offering child pornography and saved those images to the computers and hard drives, U.S. Attorney Florence Nakakuni said.

Felts admitted to downloading the images of minors engaged in sexually explicit conduct and most of the videos showed children engaged in sexually explicit conduct, including children under the age of 12, the U.S. attorney’s news release said.

Felts was ordered to register as a sex offender in any state where he lives or works and to undergo sex offender treatment.

Felts was also sentenced Monday to a five-year term of supervised release.