HOUSTON - A Houston-area plumbing company owner has been getting threatening phone calls after one of his former work trucks turned up in a photograph on a Twitter feed that appears to show a militant group fighting in Syria's civil war.

Jeff Oberholtzer traded in a Ford F-250 more than a year ago that bore the name of his father's 32-year old family business "Mark-1 Plumbing" in large white letters on the door as well as the company's phone number, according to local reports.

In the photo on the Twitter feed, the name of the company is visible and the truck has been fitted with a tripod-mounted weapon, which is shown firing off a round. The name of the militant group is seen in Arabic in the top right hand corner.

So... a plumbers traded in truck in Texas ended up part of a Syrian #ISIS 50 cal. vehicle... http://t.co/RaxntPHC5kpic.twitter.com/mGX1vHfqXC — ☣Old Photos & Bacon☣ (@photosandbacon) December 18, 2014

"To think something we would use to pull trailers now is being used for terror, it's crazy," Oberholtzer told a reporter for television station KHOU in an exclusive interview on Tuesday, adding he is no longer answering calls. He was not available for comment on Wednesday.

"We have nothing to do with terror, at all," he added.

Police have increased patrols around the business in Texas City after the KHOU report aired, according to Derek Duckett, Texas City Emergency Manager.

A spokesman for car dealer AutoNation, which acquired the truck at trade-in, said it was sent to auction and likely went through at least three dealers before ending up in Syria.

The spokesman added that Oberholtzer should have removed the company name before trading in the vehicle.