AUGUSTA, Maine — Maine State Police have found an innovative way to observe drivers texting behind the wheel, Public Safety spokesman Stephen McCausland says.

Using an unmarked van, troopers cited 23 motorists on the Maine Turnpike recently during a four-hour period, McCausland said in a prepared statement Friday. Many were texting.

As one trooper drove the van, a second trooper sat in the back observing other drivers’ activities as they passed. In addition to texting, drivers were eating, reading or using the phone, all affecting their operation.

It was the largest number of motorists cited by state police for distracted driving since the no-texting law went into effect last fall, McCausland said.

Maine’s latest highway death has been attributed to texting.

Penobscot County deputies said Tracy McPhee, 44, of West Enfield, died late Wednesday night in Eddington when her car suddenly went off the road and slammed into a tree.

An examination of her cellphone showed she had been texting moments before the crash.

Maine’s highway death toll for the year stands at 21, compared with 14 deaths at this same time in 2011, according to the Bureau of Highway Safety.