From a thick stack of papers at Alexandria police headquarters, Detective Joe Morrash pulls out police report No. 99009-532. It's the case of the missing ring.

A description of the "ladies ring, purple stone in gold setting" will be entered into his computer database--joining 1,805 other rings reported stolen in the city since 1991. Morrash then will search through hundreds of transaction reports that merchants mail to his Pawn Unit each month, on the off chance that someone tried to sell a ring matching this description.

"Everybody automatically suspects the pawnshops," Morrash said. "The idea that it's automatically going to a pawnshop is pretty far-fetched."

No question, thieves will unload stolen goods at pawnshops, Morrash said. But they also sell to secondhand stores, including antique shops and stores that purchase used computers, jewelry, guns, cameras and CDs, he said.

Like pawnshops, merchants at secondhand stores who buy items "over the counter, off the street or on the premises" are required to get a special city license and file timely police transaction reports, Morrash said.

Although all three pawnshops in Alexandria file regular reports, only about a dozen of the estimated 150 secondhand stores around the city do so, Morrash said. "A lot of the shops are buying off the streets," he said. "They're not reporting this stuff."

That makes the prospects of finding the ring with the purple stone even more dismal, Morrash said. It's also possible that the person who took the ring kept it or traded it for drugs, he said. In addition, many thieves steal in one jurisdiction and then sell in another. Although police share information, there are reporting gaps everywhere, he said.

Morrash knows that the odds of finding the ring are about as good as the national recovery rate--about 1 percent. But the detective is undaunted, driven by the fact that each of the more than 20,000 stolen property reports currently filed in his computer represents a personal loss to someone.

If anybody can get it back, his colleagues say, Morrash can. Said Lt. Ray Hazel, commander of the Criminal Investigations Section: "He's the pit bull of detectives."

Elizabeth "Spa" Wheatley is the face behind case No. 99009-532.

Wheatley was wearing the ring with the purple stone one Sunday in June while having brunch with her husband at Chadwick's restaurant in Alexandria. When she went to the bathroom to wash her hands, she placed the ring on the counter. Then her allergies started acting up.

When the sneezing subsided, she headed back to her table. In a matter of minutes, it hit her: my ring! She rushed back to the bathroom, but the ring was gone.

"It belonged to my mother's younger sister," said Wheatley, 39, an artist who lives in Del Ray. "She gave it to me on her deathbed."

Wheatley paced around the restaurant, trying to spot it on someone's finger. When she returned home, she made posters offering a reward, which she posted on telephone poles around town. Now, everywhere she goes, she searches for her ring.

"It's one of a kind," Wheatley said. "If I saw it on someone's finger, I'd know it was mine. I don't know what I would do."

Morrash has urged her to call him if she spots her ring on a stranger's finger. She has drawn a detailed sketch of the ring and its intricate setting for police, hoping that will improve the chances of finding it.

Since it disappeared, she has called Morrash numerous times to check on her ring. He patiently has explained that he will try everything he can to find it.

"I kept calling," she said. "He was very helpful."

Morrash not only works in the Pawn Unit, he is the Pawn Unit. Until recently, when a police officer was assigned part time to help him, Morrash was the unit's only officer. Without his cadre of about five civilian volunteers to enter hundreds of reports into his database each month, the unit could not function at all, he said.

"They need a lot of help," agreed Eileen G. Whitlock, 69, a retired CIA chemist who recently started volunteering. Already, Whitlock has noticed "some of the same names keep coming back" on the transaction sheets, and she flags them for Morrash to check out as possible suspects.

The Pawn Unit is composed primarily of Morrash's world--his desk, four metal filing cabinets and a bookshelf. He sifts through report after report, searching for leads or patterns. He runs items pawned with serial numbers through the National Crime Information Center to see if he gets a hit.

"He loves what he's doing," said investigator Maureen Walter, who supervises the Montgomery County police department's Pawn Unit and works closely with Morrash. "He's very good. He's very enthusiastic. There's so much paperwork. You have to have an eye for detail."

Morrash also works to get more businesses licensed, which involves photographing employees, fingerprinting and performing background checks. Some shops would rather take the risk of not having a license and avoid the extra paperwork and the required waiting periods for purchases, Morrash said. Others bristle at the thought of being lumped under a law with pawnshops, he said.

"We're trying to offer a community service, in allowing the honest and legitimate businesses to not buy stolen property either knowingly or unknowingly," said Morrash, 43. "If they get caught during a sting, they can be charged criminally."

A nearly 21-year veteran of the police department, Morrash has been in the Pawn Unit since January 1996. He says he likes the challenge and is working to change the system to improve the recovery rate.

Sometimes, tracking down some of the hottest items--computers, electronic equipment, cameras, bikes, cell phones--leads to much bigger criminal enterprises, said Morrash, who is also part of a regional FBI task force that focuses on property crime.

Because thieves move around, building relationships with other police departments is a vital part of his job, Morrash said.

"The biggest part of this is networking," he said. "It would be much more efficient if we had a regional database."

Another problem is the lack of standardization in reporting, Morrash said. What is described as a boombox by one merchant may be called an AM-FM radio or portable stereo by another, making it more difficult to match pawned and stolen items, he said.

If Wheatley's ring is ever pawned, Morrash hopes he will recognize it by the description given on the transaction sheet--assuming it's sold to a licensed business, of course.

Said Morrash: "Sometimes we get lucky and we win one."

CAPTION: Volunteer Jean French inputs information in the Alexandria Pawn Unit, which consists of a desk, bookshelf and cabinets, top.

CAPTION: On the desk is a sketch with a description of a ring lost by Elizabeth Wheatley.