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MADISON, Wis. - Thieves have been stealing hundreds of pounds of used oil from Madison area restaurants, police said.

The Madison Police Department said a DeForest company reported several recent heists of used cooking oil.

Sanimax buys so-called "yellow grease" from restaurateurs across several states. Sometimes referred to as "liquid gold," used cooking oil is processed into clean-burning biodiesel or animal feed supplements.

A Sanimax representative told Madison police that there have been at least four Madison restaurants, including the KFC on Cottage Grove Road, hit in the past month. Criminals siphoned spent cooking oil from Sanimax-maintained drums just before the company was slated to make pickups.

The market price for "yellow grease" at the time of the KFC theft was around 27 cents a pound, police said. It was estimated 1,200 pounds of grease were stolen from the eatery, valued at about $325. The Sanimax representative said the company's total company losses, from across the Midwest, are in the hundreds of thousands of dollars.

The Sanimax representative told the investigating officer that the company intends to document each case with a police report with the hope that thieves--who could be part of an organized black market syndicate--are eventually caught and prosecuted.