Alexandria police officials know exactly how they will move 18,000 pieces of evidence and other items from their property room.

Very carefully.

They're not going far -- fewer than 100 yards. Nevertheless, the move from the first floor of police headquarters to the gymnasium on the second floor will take months of planning. Evidence contaminated or lost in the process could derail a criminal case.

"This would probably be like moving a 16-room mansion," said David Miller, supervisor of the property and evidence section. "But if you're moving a household and something breaks or gets lost, you can go after the movers or just chalk it up to moving. We're not afforded the luxury of making a mistake."

The property room at the facility at 2003 Mill Rd. was to have stayed put until 2010, when the department will move to its new headquarters, the site of which is undetermined. But the first floor began to settle because of decomposing materials below the slab, and officials decided to move the property room, said Fulmer L. Collins II, who heads the department's facilities and security management division.

Collins said the department hopes to begin the move next spring. But the planning has already started.

Unlike moving a household, the property room must be accessible at all times.

"With a house, you're not trying to sleep in the bed or cook in the kitchen when you're moving," Collins said. "But you just can't shut down a property unit."

The new property room will be the 3,000-square-foot gymnasium, known as the multipurpose room, the largest space in the building that could accommodate everything, Collins said.

The current 2,400-square-foot property room appears to have every item imaginable: guns, drugs, money, DVDs, cell phones, jewelry, bicycles, officers' uniforms and equipment, bodily fluids in refrigerators, even a fur stole that sits atop a cabinet. The room holds not only evidence, but also lost or stolen items that have gone unclaimed.

"It looks half 'Court TV,' half flea market," said Amy Bertsch, a police spokeswoman. "There are murder weapons, and there are lawn ornaments."

Although the room looks like a very large, cluttered attic, employees keep track of every item with painstaking detail. Cabinets contain thousands of forms that list what is in every package, box, sealed envelope and container, Miller said.

In a separate room, evidence from current cases is placed neatly on shelves. Before moving this evidence, police officials will be meeting with a number of city representatives, including the commonwealth's attorney, Miller said. Only police employees can handle the evidence, he added.

"We have to get it right," Miller said. "Defense attorneys only need to find one thing that went wrong to say there is reasonable doubt. It doesn't even have to pertain to their case."

Some weapons were not used to commit crimes. Anyone wanting to get rid of an old firearm can turn it in to the police department; it is stored in the property room until it is destroyed. A barrel of rifles, among them what could be rare World War II Japanese rifles known as Arisakas, will probably be destroyed because bureaucratic regulations make it extremely difficult to give certain types of property away. After 60 days, the police department destroys or auctions unclaimed items, Miller said.

One such item that seems to be going nowhere is a ceramic statue of the Virgin Mary. The graceful statue, arms outstretched, is perched on a shelf, overlooking the property room with a watchful eye. Police cannot sell it at auction because of concerns about the separation of church and state, and they cannot give it away because of painstaking paperwork, Miller said.

"No one wants to destroy it," Miller said, casting a careful glance toward the statue. "Just in case the religion is right, you don't want to take the chance."

At the Alexandria Police Department's building on Mill Road, Kim Lawhorne, a public safety records clerk, puts a gun into the vault in the property room. The 2,400-square-foot room holds evidence and unclaimed lost or stolen items.Anna Spencer, a public safety records clerk, checks in a 25-pound bag of marijuana. Before moving the evidence related to active cases, police officials will meet with a number of city representatives on the details.