A big I-Team investigation busts-up an illegal back-alley car dealer. The corners it cuts puts customers and everyone on the road at risk.

The I-Team started digging into this two months ago after receiving a viewer's tip. Turns out, out tipster was right. It's a sneaky, shady operation that ignores the law to turn a quick buck.

We first met "Mike" (the name he gave us) a few weeks ago at the corner of 38th and Mitchell Streets on Milwaukee's south side. Mike told our undercover producers to meet him there to see one of the dozen or so different vehicles he had for sale on Craigslist.

When the producers showed up, Mike told them he didn't have the car they wanted to see, but he had several others for sale. Thing is, none of the cars he rattled off were anywhere around -- no car lot that we could see. A little sketchy to say the least.

Juan Munoz thought so, too. The same thing happened to him a couple months earlier while shopping around for a safe, inexpensive car his mother could drive to work.

"I thought it was kind of weird," Munoz said. "There was nothing there, nothing but warehouses, parking lots, and he drove the car out from down the street."

The car Munoz wanted was a 2001 Chevy Malibu. The ad posted on Craigslist said, "runs and drives great," and "no problems."

Not really.

"I didn't really like it, because it was leaking transmission fluid," said Munoz. "I didn't want it. My mom is handicapped, and I can't have my mom stranded anywhere else, you know, she needs a reliable car."

And just like us, Mike told Munoz, not to worry.

"He said, 'Well, we got a couple more cars in the back, if you want to take a look at them,'" recalled Munoz. "I said, 'Sure, you know, I didn't want to waste your time or mine.'"

Mike took Munoz to a nearby lot, just a few blocks away, hidden behind several of other businesses. He took our undercover producers there, too. We found Munoz's Malibu there, still for sale, with some minor improvements, supposedly.

Mike showed our producers what he said were a new battery and gaskets. He admitted the air conditioner didn't work, and the radio was gone. Still, we asked to take it for a quick spin. Good thing we had no plans to buy it.

When stopped during our test-drive to open up the hood, we saw the engine block was missing bolts, and the car was still leaking transmission fluid.

When we got back to the lot, Mike and one of his buddies told us they could fix all of it fast.

"At this point you should probably be running from this deal, quickly," said Wisconsin Department of Transportation Investigator Scott Selbach. "I mean the vehicle obviously has issues right out of the chute, and they seem like they're trying to minimize, what the issues actually are, so if it was me, I'd be running."

But what really raised the red flags with state investigators was that when our producers asked the name of Mike's business, he told them, "It's a parking lot. It's 38th and Lapham."

When the producers asked again, Mike finally gave up the name "Vegas Auto Repair." When they asked Mike for a business card, he told them he was all out.

Turns out the DOT has no record of "Vegas Auto Repair" at all.

"He doesn't have a license," Selbach said. "And you need to have a license here in the State of Wisconsin if you're going to sell cars. That's the bottom line."

By selling cars without a license, Mike makes his living breaking the law. We caught up with Mike on the same street corner about a week later.

Reporter: "Hi Mike. I'm Aaron Diamant with Channel 4. How are you? I wanted to ask you about this unlicensed dealership you're running."

Mike: "How?"

Reporter: "This unlicensed dealership you're running."

Eventually he figured out what was happening...

Reporter: "You have a license to sell cars?"

Mike: "Yeah."

Reporter: "Under what name? Because according to the state, nobody at that property has a license to sell cars."

Mike: "I mean, I'm not suppose to explain to you nothing, because, I mean, you're like nothing for me."

Reporter: "What do you mean, I'm nothing for you?"

Maybe his customers meant more to him that we did.

Reporter: "We went and test drove this Malibu here, and there was a bolt missing on the engine block, and it was leaking transmission fluid everywhere. That's not a safe car, is it?"

Mike: "Em, before I sell it, I talk to people before they buy it."

What Mike doesn't tell those people is that if they buy a car from him, or any unlicensed dealer, they give up every right they have as a consumer to go after him if something goes wrong. A very real risk.

"It's obvious he's not inspecting any of these vehicles," Selbach said.

"They're selling cars to people with low income," said Juan Munoz. "They're selling them at a cheap price, and they're pretty convincing, so I'm sure there have been others that have fallen for them."

Driving dangerous cars from an illegal dealership looking to make a buck.

"It's a shame." Munoz said. "They should be ashamed of themselves."

Our investigation continues Thursday night at 10

After seeing what the I-Team uncovered, state investigators decided it was time to shut the place down. You'll see what happened when they raided Vegas Auto Repair.