BARRY COUNTY, Mich. -- A 69-year-old Nashville, Michigan man was charged Wednesday in a horrific child pornography case involving several instances of rape and hundreds of thousands of images.

David Heinsen was allegedly in possession of more than 650,000 images and 3,000 videos of child pornography, officials say. He admitted that he'd sexually abused girls in the past, according to a release.

In 1989, Heinsen allegedly raped an 8-year-old neighbor with Down syndrome and took pictures of the abuse. The case remained unsolved until now because the girl has a limited vocabulary and was unable to describe what had happened to her, according to police.

Heinsen was arraigned Wednesday on four counts of first-degree criminal sexual conduct involving a person under 13 years of age and possession of child sexually abusive material. He was already facing a separate charge of possessing child sexually abusive material and using a computer to commit a crime.

Investigators say many of the images in Heinsen's possession were images of children of all ages, including toddlers, being sexually abused and tortured. Nashville Police Chief Chris Koster said it's the worst case he's seen in his 30 years of law enforcement.

Heinsen has been under investigation since July. His family members allegedly turned over old film they discovered to law enforcement.

When Heinsen was arrested, police say he had a gun and was going to commit suicide. Heinsen also allegedly told Chief Koster he prefers girls from 10-12 years old.

He's currently being held on a $1 million bond.

Authorities are looking other victims in this case. Anyone with information is asked to call the prosecutor’s office at 269-945-1297.