Two more catalytic converters were reported stolen off of vehicles on the University of Michigan campus, including one from a car that had been hit by thieves just a couple of weeks ago, police said.

There have been a rash of such thefts reported in recent weeks in Washtenaw County, most of them in the Ann Arbor area.

Police say the thefts appear tied to a recent increase in the value of metal. Thieves use a cordless saw to cut the exhaust pipe to quickly remove the catalytic converters.

On Friday, the owner of a 2004 Chevrolet Malibu reported the catalytic converter had been cut off the car sometime since Thursday morning in a lot in the 2100 block of Hubbard Street. U-M police said thieves stole a catalytic converter off the same vehicle on Feb. 16.

Also on Friday, a catalytic converter was reported stolen off of a 1998 Chevrolet Van parked in a lot in the 1700 block of Beal Street, campus police said. The theft occurred sometime since Feb. 14, police said.Each converter was valued at $300, though officials say replacing them can cost about $1,000. In addition, vehicles are sometimes damaged when the catalytic converter is taken.

The catalytic converter is used to convert harmful pollutants into less harmful emissions before they leave the exhaust system. It's located in the car's exhaust system, and precious metals such as platinum, palladium, rhodium or gold are used as the catalyst.

Police say thieves sell the converters to metal recyclers, who then extract the metal and resell it.

Unfortunately, police say, there are few precautions owners can take to protect the catalytic converter from being stolen.