BRIDGEPORT — Four of the city's nine fire inspectors were placed on paid administrative leave Friday after officials said an investigation of their workdays revealed they were conducting personal business while on the clock.

Fire Chief Brian Rooney identified the four inspectors as Manuel Alicea, Frank Gerardi, Lorenzo Pittman and Stephen Vitka.

A fifth fire inspector, Ronald Morales, was issued a 30-day suspension "on an unrelated matter," the chief said.

Firefighter Robert Whitbread, president of the Bridgeport Fire Fighters Association Local 834, said Friday afternoon he had just heard of the four inspectors being placed on paid leave, but hadn't spoken with them yet.

He added that Morales has been suspended without pay and would likely appeal.

The action against the four inspectors on administrative leave follows an investigation several months long, which the chief said is continuing. He added the inspectors demonstrated a "lack of accountability, cooperation and concern for work," and that they also are "difficult to manage."

The quartet apparently got themselves in hot water not long after they began using vehicles in the Fire Department's new fleet, all equipped with Global Positioning System receivers. This enabled the Fire Department's internal investigators to monitor the inspectors' actual whereabouts compared to the job sites where they were supposed to be.

The vehicles in question are all Dodge Caravan minivans, Rooney said. He said the investigation revealed the inspectors were "in places that they shouldn't have been" during the workday.

Data from the GPS supplies an accurate catalog of the precise times and locations during the day for any vehicle equipped with a GPS receiver.

Rooney, who has been chief since 2005, said the probe began after "some things didn't make sense" in the fire marshal division, where the inspectors are assigned. "The bulk of the work was being accomplished by a few," he said.

Rooney said that he hopes the investigation will be wrapped up in two or three weeks.

Fire inspectors are assigned to such tasks as inspecting multi-family dwellings, looking for illegal apartments, inspecting larger buildings for code violations, and checking buildings in the aftermath of a fire for the cause and the structure's safety.

The Global Positioning System consists of 31 medium-orbit satellites that transmit a series of high-precision microwave signals that, in turn, allow GPS receivers to determine location, speed and time. The system is managed by the U.S. Air Force's 50th Space Wing, and it's a free service worldwide.

A GPS receiver calculates its position by measuring the distance between itself and at least three of the 31 GPS satellites. Each satellite is equipped with a highly accurate atomic clock that is, in effect, adjusted to compensate for the relativistic effects of its orbital speed and the reduced-gravity environment in which they operate.

Today, numerous activities such as shipping, agriculture, trucking, surveying, banking, mobile phone operations and electricity distribution use the timing signals and position fixes provided by GPS.