DENVER (CBS4) — Drug Enforcement Agents raided at least a half a dozen homes in the Denver area on Wednesday morning after a stolen car ring led them to illegal marijuana grows. Six people have been indicted — four are in custody and investigators are still looking for the other two. They’re accused of stealing luxury cars on the East Coast and shuttling some of the marijuana out of Colorado.

Back in May or June, the Metropolitan Auto Theft Task Force received information about a person who may be selling VIN-switched high-end vehicles. The task force looked into it and found multiple VIN-switched vehicles — which led to a group of individuals involved in the illegal manufacturing and distribution of marijuana.

DEA agents recovered illegal marijuana plants and processed marijuana that was packaged for distribution in homes in Aurora, Federal Heights, Thornton and Denver. They also found processing equipment used to make marijuana hash oil.

“They use butane in the process of converting processed marijuana and stems into THC oil which is a highly pure form of THC. Some of this stuff is up to 90 percent. There is a huge danger, fire danger, explosive danger, with these butane honey oil labs,” said Special Agent Tim Scott. “And some of these houses are in residential neighborhoods.

They say the marijuana was distributed in multiple states, including Colorado, Georgia, Florida, Tennessee, Arizona, Maine, and California.

Investigators also recovered 17 stolen high-end vehicles with a total value of $1.2 million — as well as large amounts of cash and firearms.

“Criminal organizations use the marijuana industry in Colorado to operate in not only black-market marijuana cultivation and distribution, but also many other criminal related activities,” said Special Agent in Charge [SAC] of the DEA Denver Field Division William McDermott.

“There is so much black market marijuana here, there is not a neighborhood probably in Colorado that is not impacted by this. I’m talking million-dollar-plus homes all the way down,” one investigator said Wednesday. “Rentals are a big thing we see all over the place… They’re in every neighborhood.”

Investigators talked about some of the signs that might indicate an illegal marijuana grow at a house.

“If you’re in a neighborhood and you’re in a 1,200-square-foot ranch style home and you have three of the largest air conditioning units in the back of your house, that’s a pretty good sign you’ve got a marijuana grow,” said Agent Scott. “When you see people coming and going in the middle of the night, you see U-Hauls regularly showing up to the house, you see extra venting being cut all around the house, when you see windows in the basement and the garage sealed up so you can’t even see in, those are all indicators of a marijuana grow.”

“In the winter you’ll see homes actually sweat. You’ll see ooze coming down the sides of the homes because of all the humidity inside the home. Another indicator of a marijuana grow,” Scott said.