Mick Swasko/TribLocal reporter

Three people were arrested for operating what police call a highly sophisticated marijuana growing operation in Bolingbrook and Naperville that included more than 7,500 cannabis plants in three locations, Naperville police said Wednesday.

Bail was set at $1 million Tuesday for a 40-year-old Chang Hai Chen, who is accused of cultivating more than 7,500 marijuana plants at three houses he rented — one in Naperville and two in Bolingbrook.

Naperville police said a report of suspicious activity led them to obtain a search warrant for the residence in the 2500 block of Whitehall Way rented by Chen. Once inside, police said they discovered a large-scale cannabis growing operation with 1,500 plants.

Additionally, police discovered information that led them to execute search warrants for two residences in Bolingbrook where 6,000 additional plants were found, police said. The Bolingbrook police and Drug Enforcement Administration assisted in obtaining the warrants.

Also arrested were Mingdi Lu, 30, of Bolingbrook and Jinzu Shi, 51, of Chicago, Naperville police announced Wednesday.

Naperville Police Sgt. Gregg Bell said there was no formal investigation that led to the arrests, and Naperville police are continuing to investigate.

“We got a call, we followed up on the call, and it was kind of a domino effect after that,” he said of the discovery of the operation. “This is probably one of the largest numbers of plants that have been confiscated (by Naperville police).”

DuPage County Assistant State’s Attorney Ken Tatarelis told Judge Liam Brennan in bond court Tuesday that the plants Chen is accused of illegally growing were worth more than $10 million. Chen lives in Chicago.

Chen apparently had illegally tapped into area electrical grids to power the three operations, Tatarelis also said.

Chen was charged with felony possession of cannabis, a class four felony that carries a penalty of up to 15 years in prison. Lu was charged with felony production/possession of cannabis, a class three felony with a possible three to seven years in prison, and Shi was charged with felony production of cannabis, a class two felony carrying a penalty of two to five years in prison.

Lu was transferred to the Department of Immigration from the Will County Jail Wednesday, and Shi is being held on $30,000 bond, but has an immigration hold placed on him. Chen remained in custody in the DuPage County Jail Wednesday afternoon.

Chicago Tribune reporter Art Barnum contributed to this report.