An employee of Sheehy Lexus of Annapolis discovered the thefts at 6:30 a.m. Friday when he started one of the vehicles at the lot at 121 Ferguson Road, which parallels eastbound Route 50 just off Bay Dale Drive, said Alan Kassel, the general sales manager.

The employee knew the roaring sound coming from the vehicle could only be one thing.

"As soon as you start it, it's like you don't have a muffler," Mr. Kassel said.

The tally of damaged Lexuses kept increasing, with a total of 28 catalytic converters sawed off of the dealership's new vehicles and two off customers' vehicles. The new exhaust components are valued at $2,000 apiece, adding up to a $56,000 overall loss for Sheehy Lexus, according to the police report. The value of the two units cut off customer cars is unknown.

Two catalytic converters and two reciprocating saw blades were left behind, police said.

Police took the recovered exhaust systems, saw blades, and plastic bottle for evidence, and a team of technicians dusted vehicles for palm and fingerprints. Black powder could be seen on the sides of several sport utility vehicles at the lot yesterday afternoon.

All of the vehicles targeted were SUV's, and were parked outside a fence on the left side of the showroom, Mr. Kassel said.

"It was all the cars outside the fence on the upper lot," he said. "All were SUV's. It'd be too tough to get under the car to cut the exhaust system off."

He said experienced catalytic converter thieves can yank the exhaust system in just minutes.

"With a professional - two cuts and it'd probably take five minutes for each one," he said.

Thieves can get $6 to $150 per catalytic converter at scrap metal dealers, depending on the type of exhaust system and what precious metals are inside, an employee of Halethorpe-based Converter King said.

Police do not know how many people were involved with the thefts. They're collecting surveillance video from Sheehy Lexus and neighboring Jaguar Land Rover of Annapolis, said Sgt. John Gilmer, a county police spokesman. And a detective has spread the word to scrap yards in Anne Arundel and neighboring counties to be on the lookout for shiny new exhaust systems - especially if they're in bulk, he said.

This is the second time the lot has been struck in about a year, Mr. Kassel said. A year ago, he said thieves took off with 10 catalytic converters from vehicles parked on the lot.

The dealership has hired a security company and has added more cameras to prevent future thefts, he said.

The theft of catalytic converters is a phenomenon occurring up and down the east coast, from New York to Georgia, county police have said. More than 500 catalytic converters have been stolen in the county this year, police said.

Thieves are targeting park and rides, car dealerships, salvage yards, and other large lots where there are plenty of vehicles to choose from. Catalytic converters contain high amounts of metals with increasing values that thieves sell at recycle centers. Scrap dealers don't require identification from people who are selling them, police said.

A detective with the Criminal Investigations Division has been assigned to specifically investigate metal thefts in the county.

Police have made multiple arrests for catalytic converter theft this year.

Late last month, two men were charged with theft after allegedly stealing 14 catalytic converters from cars parked in front of a Glen Burnie business.

Two weeks prior, police charged two men after three of the exhaust systems were found in their vehicle during a traffic stop in Severna Park.

And in April, two men were charged after police said they found catalytic converters and cutting tools during another traffic stop in Severna Park.

Police believe some of the men arrested are linked to several other catalytic converter thefts that are under investigation.