He works 8 to 5, never on weekends and Fairfax County police believe he may have burglarized as many as 23 houses in recent weeks in the West Springfield, Annandale and Fairfax areas of the county.

Police estimate that the thief, which they have dubbed "the piggy bank burglar" because he empties piggy banks and takes wallets and checkbooks, has stolen about $10,000.

The string of burglaries began on Sept. 14, but it was not until recently that police realized a pattern was forming and that one person may be responsible for all of them.

"Everything fits -- the old MO," officer Connie Novak, the police department's Crime Solvers coordinator, said yesterday. "What makes this stand out is that they're happening almost everyday."

With the exception of two lulls, the burglar has struck at least once between 8 a.m. and 5 p.m. every weekday in a concentrated area in the eastern part of the county, said Novak. The most recent burglary was Monday, sometime between 10 a.m. and noon, she said.

"We were gone for one hour," said a 56-year-old Annandale resident whose house was burglarized on Oct. 15. She said that when she and her 60-year-old husband returned from the store, a wallet, a checkbook and about $25 in change that they used for Metro fares were missing.

The burglar, who entered the house through a cracked second-story window, later cashed several of the checks, totaling $1,125, said the woman, who asked not to be identified. "Can you believe it? And of course the banks gave it to him. He did a very nice forgery on the checks."

In most cases the suspect, described only as a white male about 6 feet tall, has entered the houses through unsecured second-floor windows, sliding glass doors or entrances hidden by heavy foliage, Novak said.

In addition to cash and checkbooks, Novak said the burglar also has taken silverware, a Canon AE-1 camera, handguns and video equipment.

The burglaries have occurred in areas including Old Keene Mill Road, Bardu Avenue and Queen Elizabeth Boulevard, Novak said. She said police are offering a reward for tips leading to the burglar's arrest and conviction, and anyone with information should call Crime Solvers at 691-8888.