Until two years ago, Alexandria Sheriff's Deputy Mike O'Toole used to put prisoners in his Plymouth Duster to transport them on long journeys to state prisons or testing facilities scattered throughout Virginia.

Things improved when official cars replaced the deputies' private vehicles, but now O'Toole's boss, Sheriff Mike Norris, thinks he has a better idea. He wants to buy a twin-engine airplane to do the job faster and, he believes, cheaper.

And not an expensive airplane, either. Norris said he had discovered that under a federal program begun in 1976, he could obtain a surplus government plane valued at $100,000 or more for as little as,1,000. Norris now is drumming up support in neighboring Fairfax and Arlington counties to help share the cost.

If successful, the Alexandria sheriff's department would become the first in the metropolitan area to own or lease its own airplane.

"Our problem is that the Virginia state facilities for testing and observation are located at the far end of the state, in places such as Staunton and Marion, and by the time we get there and back it's a two-day trip," usually involving two deputies, Norris said.

"If we had a plane we could do the whole thing in five or six hours, and possibly save money and manpower."

Alexandria's 54-member sheriff's department is responsible each year for about 2,300 people awaiting trial, according to chief deputy O'Toole, who is in charge of the airplane search.

The department also is responsible for the delivery of legal documents, such as subpoenas and eviction notices.

"Each year we make about 75 trips a year to the Powhattan correctional facility near Richmond, 130 miles one way, 27 trips to the juvenile facility in Southampton, about 200 miles one way, 50 trips to the Southwest State Hospital in Marion, about 333 miles one way, and 100 trips annually to Staunton, about 135 miles one way," Norris said.

"That takes up so much of our time that we have fallen behind on the service of papers, and have received complaints from judges and lawyers."

The sheriff's department in Montgomery and Prince George's counties considered and rejected the idea of buying airplanes several years ago, because diagnostic facilities for Maryland prisoners are located in nearby Baltimore, according to officials in both counties.

"We would use the 'doughnut theory' of transportation for figuring out whether to use a car, a small plane, or a commercial airplane," said O'Toole. "If a facility was within the doughnut hole, we'd use a car or van, if it was within the 'meat' of the doughnut hole, we'd use a car or van, if it was within the 'meat' of the doughnut we could use the small plane for flights up to about 750 miles, and beyond that we'd book space on commercial planes," he said.

Fairfax County Sheriff James D. Swinson and Arlington County chief deputy Charles N. Gray each said their departments would be willing to participate with Norris if he could prove to them that a plane would save them money.