In the darkest corners of the Internet, "for sale" signs are popping up for some troubling products. From fake IDs to illegal drugs to high-powered weapons.
"We're looking at an offer to sell and army tank and rocket launcher," said a Dark Net expert as he pointed out Dark Net sales offers.
Several layers beneath the World Wide Web most of us know, this "Craigslist for Criminals" is known as the Dark Net.
The Dark Net is basically a set of Internet tunnels where people go to anonymously act in the dark. But just like with a real tunnel, you eventually have to step out into the light.
It's a hiding place where IP addresses disappear and data is encrypted -- a place law enforcement agencies would prefer nobody knew about.
In fact, a few departments refused to even discuss it with us. And the FBI has even halted investigations into Dark Net activity, saying it's impossible to trace.
Action News consulted with a computer intelligence expert who asked to be disguised because of the dangers of exposing these criminals and their devious activities. He took us to an underworld exchange focusing on identity theft.
"This is a text snapshot of credit card requests and credit card offers to sell," he said as he showed us a simple Dark Net page.
A simple search turned up hundreds of victims on a single site, including Katie Nicholas.
"I looked on my bank account and I saw a whole bunch of transactions that had either gone through or been pre-authorized," she said.
Dark Net users sometimes use currency called "bitcoins", but also barter contraband for contraband -- as with child pornography.
That's what Brian Haney is trying to track. The Tulare police detective has spent five years with the Internet Crimes against Children task force, often watching the Dark Net tunnels, waiting for criminals to climb out.
"Most of these guys are going to pop up at some point in time," Haney said. "They're going to share a file or they're going to download a file or they're going to send something via email."
Haney acknowledges the difficulty of breaking down the tunnel walls to find people victimizing children. But a single clue can lead to a search warrant to uncover the trophies brought back. And eventually, he says, police will catch nearly every cybercriminal.
"For every genius working in the programmer world trying to figure out how to hide from us, we have equal geniuses on the law enforcement side trying to find back doors into their evil genius' ways," he said.
Until they can break down those doors, investigators will keep an eye on the exits, waiting to see what walks out of the dark.
You can take some steps to protect yourself from being a "Dark Net" victim. Change your online passwords often and shred financial documents before throwing them away.
Experts say trying to monitor your "Dark Net" profile is a dangerous idea. It's hard to find in the first place and you can easily end up somewhere you really don't want to be.