Guangguo Li, 48, of Oshkosh, and Zhengwei Xu, 42, of Chicago, each face a misdemeanor theft charge and a felony charge of possessing burglarious tools. The charges are accusations; both men are presumed innocent unless proven guilty.

Police were called to Panda Garden, 922 Windsor St., at about 2:33 a.m. after someone watching the restaurant’s security camera reported two men taking oil from a container behind the business. The caller described a white box truck and occupants wearing high-visibility vests, the complaint says.

A sergeant soon spotted a matching truck nearby. The men told the officer they were collecting cooking oil, and officers found six large containers in the truck, according to the complaint. Investigators also reported finding a saw and crowbar. The restaurant’s oil containers were locked, and neither man had a key; investigators allege the lids were pried open or lifted to remove the oil.

Xu told investigators he was driving and had been hired online by someone he had never met. He said he received restaurant locations through a messaging app and had been in Wisconsin only a few days, according to the complaint. Li, speaking through a Mandarin interpreter, said he operated the equipment used to pump the oil and was helping his boss, but struggled to identify his employer, the complaint states.

The complaint says Xu directed investigators to a woman who identified herself as “Amy” and a manager at Safe Energy LLC. She told officers the company made one or two monthly collection stops in Sun Prairie, typically at Asian restaurants, but could not provide contract information or identify other collection locations, according to the complaint.

Panda Garden employee Ting Gou said the restaurant has been targeted repeatedly, including in an incident captured on video in July. Gou estimated the latest theft at about 30 gallons and said the repeated incidents have cost the business thousands of dollars over the years. She said the restaurant has a legitimate used-oil collection contract with Sanimax.

Police also noted possible tampering at a nearby Pizza Hut oil container, according to the complaint, but have not confirmed a connection to the Panda Garden case. Sun Prairie Police Sgt. Tommy Foy said the department began receiving cooking-oil theft reports around 2024 and continues to hear from local businesses.

Foy said restaurant owners may not notice thefts if they assume their regular collection company has picked up the oil. He urged businesses to monitor security cameras and check containers for signs of prying or cut locks.

Investigators are contacting neighboring municipalities and state and federal agencies to assess whether similar reports are related. The complaint also refers to a separate federal case involving alleged organized theft and resale of used cooking oil across several states. Police have not alleged that Li or Xu are connected to that case and say they have no evidence of a link.

“It’s still too early in the investigation to say if it’s a large crime, or if this is a crime of opportunity of some individuals,” Foy said.