About 40 gallons of used cooking grease were stolen from the Post Road Diner, 312 Connecticut Ave., early Wednesday morning.
A manager told officers an employee found the lock cut to the diner's used grease storage container at about 4 p.m. A surveillance camera showed a man siphoning grease out of the container at 1:30 a.m.
An officer reported the video showed the man inserting a large hose into the container. The video was not sharp enough to reveal the license plate of the man's truck.
The theft of used cooking grease has become prevalent across the country. Processing plants convert the grease into biodiesel.
An employee of BioPur in Bethlehem, CT, said on Thursday it's a big problem for the restaurants and her company. She said restaurants are paid between $1.25 and $1.50 per gallon, meaning the theft at the diner meant a loss of between $50 to $60.
"The restaurants are losing a lot of money, and we're losing a lot of product," she said.
The woman, who declined to have her name published, said storage containers behind restaurants range from 55 gallons to 200 gallons.
BioPur's website says it produces over 400,000 gallons a year of "pure biodiesel."
The website for the National Biodiesel Board, a trade association, says biodiesel is made from agricultural co-products and byproducts such as soybean oil, other natural oils, and greases, and is used as a diesel substitute that burns cleaner than petroleum diesel.