A Chicago police officer and a Cook County sheriff’s deputy in a helicopter spotted the crop on Tuesday as they headed back to their hangar about three miles away.[1][2] The plot, about the size of two football fields on the city’s far South Side, had been hidden under a canopy of trees and surrounding vegetation.[1][2]

On Wednesday, officers chopped down about 1,500 plants in what police called the largest marijuana farm anyone at the department could remember.[1][2] Police said the growers could have earned as much as 10 million dollars from the harvest.[1][2] No arrests had been made and police were still trying to determine who owned the property, though they hoped the size of the operation would bring tips, including about a man seen running as the helicopter swooped low.[1][2]

Narcotics commander James O’Grady said officers had never seen anything like it, in part because Chicago’s harsh winters leave growers far less time than counterparts in California or Mexico, and the crop had likely been planted in spring.[2] Pilot Stan Kuprianczyk and deputy Edward Graney said the crew had the right altitude, angle and sunlight, and recognised the brighter green shade after training on a smaller suburban grow weeks earlier.[2]