Some employes at a Fairfax County vehicle maintenance garage have been ordering parts for school buses and other county vehicles and stealing them, county officials said yesterday.

An employe at the garage at 4620 W. Ox Rd. told The Washington Post he has given police documents that show the workings of the scam, which has been going on for more than a year.

Police Maj. Michael W. Young, commander of the criminal investigations unit, said an informant has produced documents that show an "almost absolute indication that something was inappropriate." Young said yesterday the investigation is continuing.

The informant said garage employes filled out work orders for parts needed for school buses and other county vehicles and "blended in parts they didn't need, but wanted." For example, he said, if a dishonest employe was repairing a school bus, he would bill the school board for both the necessary and unnecessary parts. Among the unnecessary parts, according to the informant, were oil pumps, at $50 each, and lifters costing $74 a set.

"Auditing has known there has been stealing going on for years but they could never prove how the equipment was getting out of the garage," the informant said.

Two mechanics at the garage, John W. Griffith, 42, of Purcellville, and Charles H. Aronhalt, 36, of Round Hill, were arrested last week on charges of stealing parts valued at about $400. They have been placed on administrative leave.

County Executive J. Hamilton Lambert confirmed that the county "has had information for a year or more that things may been been going awry." He would not speculate about the size of the operation, except to say that the thefts "were in the thousands."

"We first got involved . . . probably a year or two ago," said Ronald Coen, the county's director of internal audits. "There have been some inventory shortages on occasion, and allegations by various persons as to shortages."

Coen said most errors were clerical but recently "an employe came to us and made some allegations. We looked at the documentation and felt it was enough to warrant an investigation."

The West Ox garage, the largest of three such county facilities, employs 81 people and provides maintenance for about 3,000 vehicles, including 820 school buses. Last year the garage, which had a $3.5 million budget, processed 21,954 work orders at an average cost of $173.