Child pornography cases are among the most disturbing Postal Inspectors investigate. And modern technology is making it much easier for criminals to distribute child porn and more difficult for victims to recover.

"He was a registered nurse at a pediatric hospital. He was in charge of several children," explained US Postal Inspector Kathryn Lara.

Authorities say he abused at least two boys in his care.

"He befriended this child who had emotional issues and came to have a special bond or friendship with this particular child. The boy, in turn, trusted him so it was easy to take advantage of that," said Lara.

The nurse's second victim, Lara explained, "He was left alone with the child. It was a night of babysitting and it was an opportunity that presented itself."

Postal Inspectors discovered that the nurse in this case was involved in another crime.

"We found that he had at least four external hard drives filled with child pornography. He had magazines and books that contained images of children in various stages of undress," she said.

A total of 4,000 to 5,000 images.

"As technology has evolved, the ability to produce child pornography, trade and distribute child pornography has become so easy for predators," said Assistant US Attorney Robert Stabe.

The internet has made distribution simple and immediate.

"Three predators continually recirculate, share and trade these images. They're forever there, they never disappear," Stabe explained.

They remain on the internet to the dismay and horror of victims.

"Anytime someone watches that video of that child, they are continuously being victimized," said Lara. "I have heard from one victim who said it doesn't matter how old she was when it happened, it's like it happened yesterday."

The male nurse in this case was sentenced to six and a half years in prison on federal charges of possession of child pornography.

Authorities advise parents to always be vigilant. If your child's behavior changes dramatically or you see signs of bruising, seek professional help to determine if your son or daughter has been sexually abused.