HINGHAM, Mass. (AP) – As snowplow driver Paul V. Gratta made his rounds during a fierce winter storm, the state police troopers tailing him say they saw him stop along the road, put a device tracking his movements in a paper bag and leave it sitting in a pile of snow.

With the global positioning system sending out its signals from the snow bank, it would appear to Massachusetts Highway Department officials keeping tabs on the crews clearing snow that Gratta was idling alongside the highway.

But Gratta was actually doing more lucrative private plowing jobs at the same time he was being paid $105 an hour by the state, Attorney General Tom Reilly said.

“He was pretty crafty and shrewd,” Reilly said at a news conference near the same stretch of Route 3A where Gratta was making his rounds. “He left that GPS in that bag near where they generally stop for coffee. So that would have been the explanation for that: that he had stopped for coffee or to get a bite to eat.”

For the apparent double-dipping, Gratta, 50, of Cohasset, was charged Friday with fraud and larceny, along with employee and alleged accomplice Frank Eddy, 33, of Hull.

Both pleaded innocent at their arraignment in Quincy District Court and were ordered to return to court on April 14.

Gratta, owner of Hull-based Hub Construction, has been a state snow plow contractor for 15 years, said his attorney, Robert L. Jubinville.

“It seems to me to be a big fuss about nothing. It’ll work itself out through the court system,” Jubinville told The Associated Press.

The alleged scam was an end-run around the GPS system that MassHighway put in place last winter. Worried about fraud, the state began requiring its plow drivers to bring along a phone containing GPS technology, so officials would know whether they were doing the assigned work.

Last Monday, the day before the most recent storm to hit the state, police got a tip about Gratta. As the snow piled up, a trooper stationed himself near Grampy’s, a convenience store where plow drivers often congregate between runs, according to store manager Steven Barry.

“They come in all the time to get coffee,” he said. “Sometimes they’re there 10 minutes, some they’re there longer.”

The trooper watched as Gratta allegedly dropped the bagged GPS phone on a snow bank. He then drove off to plow the driveway of a Cohasset nursing home – a job that paid him $135 per sweep, authorities said.

As he returned, he may have realized he was being followed because he turned off his lights, Reilly said.

Then Gratta gave the phone to Eddy. While Eddy plowed the state highway, Gratta allegedly went off to do more private work.

Reilly said the fraud is probably not limited to the two men, but it’s not clear how many drivers may be double-dipping. One solution would be to mount the GPS devices inside trucks, so they can’t be removed, he said.

“I think this will send a very strong message” to other snow plow drivers working for the state, Reilly said.

Private contractors provide 5,100 plows and salters for the state, and all of them carry the GPS technology, according to John Carlisle, spokesman for the state Executive Office of Transportation.

Carlisle said he believes fraud by plow drivers has diminished since the state began using the GPS devices.

“You’re always going to have your bad apples. That’s unavoidable. Some people will always try to beat the system,” he said. “The vast majority of people who work for the state do great work, and they’re honest and do a great job.”