Catalytic converters are part of a vehicle's exhaust system that help reduce harmful emissions.
Foster's Auto Body, located at 7300 Capital Blvd., on Monday reported 13 catalytic converters stolen from vehicles awaiting repair. Other items also were stolen from the shop, police said.
The following day, another 18 catalytic converters were stolen from vehicles at J&J Automotive in the 3800 block of Capital Boulevard, police said. Seventeen of the tampered vehicles belonged to customers, while one belonged to a shop owner.
Some stolen catalytic converters wind up being used on other vehicles, police said. Some are disassembled to recover small quantities of precious metals found inside them, such as platinum, palladium and rhodium.
"They contain some small amounts of relatively rare metals," said Jim Sughrue, spokesman for the Raleigh Police Department. "If they're stolen in quantity and somebody goes that route, there's a few dollars per converter that can be made."
Police said they believe the two thefts to be connected because of the similarity of the crimes and the proximity of the two repair shops that were hit.