HOUSTON -- A gasoline tanker scam was broken up with three arrests after undercover Houston police officers tailed a semi with video cameras, Local 2 Investigates reported Friday.

"It feels like cheating to me. It's real bad," said victim Richard Yim, owner of Star Mart on Bellfort in southeast Houston.

He and other gas station owners paid a local tanker delivery firm for gasoline, but prosecutors said they were being short-changed by hundreds of gallons. That gasoline was then delivered to another station that had not paid the tanker delivery firm.

Assistant Harris County District Attorney Kimberly Miller said, "The owners of the company were notified that their regular customers were getting shortages, so they looked into the particular truck delivery and there was a GPS (Global Positioning System) attached to the truck. Based on where the GPS was going, they were able to determine that this truck driver was actually making deliveries that he wasn't supposed to."

Undercover officers from the HPD Major Offenders Division were recording with a video camera at one gas station on Mesa Road in northeast Houston, where the GPS had led them.

Tanker truck driver Gerald Allen Green, 47, was captured on tape hooking up hoses and emptying hundreds of gallons of stolen gasoline into the tanks at that Mesa Road business, which was not a legitimate customer of the tanker delivery service, according to prosecutors.

"He's draining the hose," said one undercover officer on the tape, which is now being used in court as evidence.

At that point on the tape, Green is seen lifting a hose and forcing extra gasoline out into the underground tanks as he was finishing.

Green was arrested after one of those deliveries.  He pleaded guilty to theft charges and is currently serving a six-month term in prison.

The manager on duty at the Mesa Road gas station, Bilal A. Ghauri, 46, was also arrested since prosecutors said he accepted and kept records on some of the deliveries of stolen gas. He pleaded guilty to theft and is serving a 160-day sentence in the Harris County Jail.

Gas station owners like Yim started noticing that they were paying for more gas than they were receiving. Some station owners checked with long measuring sticks that are dipped into the underground tanks, but Yim pointed to an electronic system that measures gas in his underground tanks.

"(He was) supposed to put in 8,000 gallons of gas. It shows around 76 or 7650, about 400 or 500 gallons short," he said.

He said each time he was short-changed could have cost him around $1,500, but it didn't stop at his one store.

"I have another store. He stole at that store about three times," he said.

Yim pointed out that he was only short-changed on nighttime deliveries, when there is less likelihood of someone double checking the amount that was actually delivered.

"I look at it and it wasn't right," he remembered from checking his computer after Green made one delivery.

Miller, said, "They were able to determine it was six thefts, and the amount that they were able to determine is in the range of $11,000."

The owner of the Mesa Road gas station that received the shipments, Nisar Ahmad, 48, was also arrested and charged with felony engaging in organized criminal activity. He has pleaded not guilty and is awaiting trial.

When a reporter entered his store Friday, he was reached by telephone and said he is innocent.

Ahmad said, "I didn't know the gas was stolen or anything."

He said a customer who owed him money arranged for the first gasoline delivery from Green's tanker. Ahmad said the customer told him after that delivery, "Don't worry, I owe you nothing (now.)"

But Ahmad said Green came into the store yelling and demanding more money beyond that settled debt, and so Ahmad said he paid him.

He said he paid Green about 20-cents per gallon below the going market price.  He said he didn't remember whether that first delivery was 50 gallons or 500 gallons.

Ahmad said Green later returned and indicated he was going to be opening his own gasoline delivery service that could offer a bargain in the future.

Ahmad said no price had been agreed upon, but when another delivery of gasoline was made, "I thought he must already have a small company or something. I was not sure what he was doing."

Ahmad said he will fight the charges in court. He is due in court for another hearing on July 16.

HPD officers assigned to the case did not return phone calls from Local 2 Investigates.

The tanker driver's jail sentence was longer because of something that officers caught on tape when they were watching one of the deliveries. Miller said officers saw Green spill more than five gallons of gasoline when he was handling one of the hoses. That led to a charge of illegal dumping, for which Green also pleaded guilty.