It is a mystery. Not the Sherlock Holmes variety. More like the who-cares variety. But a mystery nevertheless.

It starts with the bowls. Four of them, deposited by someone, under the huge spruce that stands in front of the seat of Fairfax County government, the Massey Building in Fairfax City.

Someone -- and no one around the towering government building can figure out who -- has left a large bowl filled with dry cat food, three bowls of water and a bed of straw underneath the tree.

The bowls are refilled on a periodic basis.

Amerjit Sodhi and Ann Anderson, who work at the information desk in the lobby that faces the spruce tree, said they have not noticed anyone leaving food for cats.

Employes in the building's cafeteria said they saw a feline family around the construction site for the new county jail, which is adjacent to the rear of the Massey Building, but they have no idea who would leave food for them.

Security guard Don Bowen Jr. said he heard about the cat family "quite a few years ago" but did not know where they are now. He thought maybe the employes who worked the midnight shift in the computer room left the food, but he could not be sure.

The mystery deepens.

Alan Spencer, who maintains the grounds around the Massey Building and who, of all people, should know what happens in his domain, said that, yes, he saw the bowls of food under the tree recently, but no, he did not see who put them there.

"I saw those cats about a month or two ago and tried to get them, but they're too wild," Spencer commented.

The secretaries in County Executive J. Hamilton Lambert's office, whose 11th floor office overlooks the front of the building, have seen neither hide nor hair of the cats since last summer.

"I remember a dog being lost last year," said one secretary.

Claudia Lewis, who walks by the tree on her way to work in a city law firm, surmises that the cats come out at night to eat and that they hide during the day. As for the person feeding them, "It shows that there are some nice things that go on," she said.

The bowls of water, the cat food and the straw have gone unnoticed by most passers-by. And so have the cats, for that matter.

The mystery remains.