State police heard voices.

They were watching a school bus videotape to see if the bus was dangerously overcrowded.

But the voices on the tape turned their investigation in a whole new direction.

"Our laws protect people from being recorded without their permission," said Trooper John Marks, of the Vehicle Fraud Investigations and School Bus Safety Unit.

Officers seized about 70 camera systems last week from buses parked at Laidlaw Transit Inc.'s Dravosburg station, along with more than 100 videotapes, which they believe also contain illegal audio recordings.

"We have to review each tape to support the actual charge, but we are reasonably sure when we review the tapes we'll find video and audio recordings," said Trooper Marks.

A Laidlaw bus driver had claimed the company pressured him to drive an overloaded school bus and then suspended him without pay when he complained.

State police got involved because overcrowding on a school bus is a safety issue.

The video showed the bus indeed was overloaded, but because the on-board camera also recorded sound, the company might be charged with taping people without their knowledge, a third-degree felony.

No charges have been filed yet against Laidlaw, a multinational company.

A third-degree felony is punishable by not more than seven years in jail and a fine of up to $15,000 per charge. If taken to the full extent of the law, Trooper Marks said, that could mean separate charges for every bus and every student that was recorded on any given day.

The Allegheny County district attorney's office will make that decision.

Dave Armit, vice president of operations for Laidlaw Education Services in New Jersey, did not return several telephone messages yesterday.

The video cameras were mounted on the buses' ceilings behind the drivers and above the center aisles for safety purposes. Trooper Marks said cameras had been installed on many buses, but not all of them.

The suspended school bus driver asked state police officers to view the tape to support his claims. He had been assigned to drive elementary school students in the West Mifflin Area School District on a field trip in December and the bus was overcrowded. He told Trooper Marks a similar dispute had occurred in the past in which he believed he had not been well-supported by the company.

Pennsylvania's wiretapping laws are among the most restrictive in the nation. Audio recordings are illegal unless the person recorded is aware and gives consent.

"At this point, we haven't expanded our investigation outside of the Dravosburg terminal," Trooper Marks said.

"There are other terminals, companies and school districts that we know have at least video on their buses. But for now, this is where we have the actual evidence of audio taping."