Someone broke into a state police cruiser parked as an anti-speeding decoy along Interstate 95 in Harford County and stole a trooper's uniform shirt and Stetson hat off a dummy inside, emergency lights off the top of the car and an electronic transmitter, state police said yesterday.

The thefts occurred while the 1989 Chevrolet Caprice was parked off the shoulder of northbound I-95 about two miles south of Route 152 near Fallston overnight July 4, said Cpl. Glenn Gitschier of the John F. Kennedy Barracks in Perryville.

State police had been parking the cruiser alternately beside the north and south lanes of the interstate near the Harford-Baltimore County line to slow speeders. The stolen transmitter emitted a signal to activate motorists' radar detectors, the corporal said.

A state police investigator reported that someone bent the right front door and frame of the decoy cruiser with a pry bar to get in.

State police estimated the damage and loss, including the $500 transmitter and $300 emergency lights, at $1,389.