The New Lenox police also reported catalytic converter crime in their town in recent months.
"It's a very common thing," said Frankfort Deputy Police Chief Kevin Keegan. "It seems to be happening at the Metra stations because they know people are going to be gone all day."
Keegan said the Frankfort police arrested and charged alleged thieves with stealing catalytic converters in the fall.
An emission control device, a catalytic converter contains "precious metals that act as catalysts," according to Nationwide Insurance's website.
"With the price of precious metals skyrocketing, thieves are helping themselves to catalytic converters that contain enough platinum, palladium or rhodium to make it worth the risk to cut it from the underbelly of your vehicle," the site said. "You might become aware that your catalytic converter has been stolen when your vehicle starts with a gravelly roar."