When Houston-area plumbing company owner Mark Oberholtzer sold his truck to a local dealer in October of 2013, he had no idea it would wind up on Syria's front lines being used by ISIS fighters -- with his plumbing company name and phone number still on the side.

"You know, it hurts my feelings, that anyone could possibly thing that we were connected to terrorism in any way," Oberholtzer told CBS News.

He says he was assured by the dealership that it would remove his information before selling the truck. But there it was in the photo -- which then went viral.

A picture showing Mark Oberholtzer's truck -- including his company's name and phone number -- went viral last year after it was posted on an Islamic militant group's Twitter feed. KHOU

It was featured on the last episode of "The Colbert Report," seen by millions of people earlier this year. Since then, Oberholtzer says he's had threats and thousands of phone calls like this one.

"What the f--- is going on?" one message said. "Are you selling your truck to ISIS? Who did that? That's not right!"

Here's how the truck left the country: Oberholtzer sold the truck to an AutoNation dealership in Houston, which sent it to an auction near Dallas.

Then a used car dealer, Maz Auto, bought the truck, the manager confirms, with the lettering still on it, and advertised it for sale on their website.

Manager Mohamed Alkhawam told CBS News someone called from an international phone number and arranged to buy the truck for use in Turkey.

"He wired the money, and he arranged for shipping ... and that was it. The car ended up being shipped to Turkey," Alkhawam said.

It's not known exactly how the truck then made its way from Mersin, Turkey to Syria.

"You used to have 'Mark-1 Plumbing Inc.' would come up on the Internet," Oberholtzer says. "Now it comes up 'Mark-1 Plumbing Inc. ISIS."

He's now suing the AutoNation dealership that sold the truck for $1 million.

AutoNation did not respond to CBS News' request for comment, but an executive told CBS affiliate KHOU that they thought the auction company was removing the decals.

The auction house could not confirm for CBS News that it sold the truck.