On December 5, 2009, Cook County sheriff's police sergeant Patrick Donovan spotted two men in a white, windowless cargo van on the loading dock of a shop called the Brew and Grow, tucked between Elston and the Kennedy expressway. Donovan watched from his car 40 yards away as the men—one of them medium height and stocky, the other tall and gangly—loaded large tables, fans, and four-foot filters into the van.

The Brew and Grow, which has since moved, sells tools and equipment for home beer making and hydroponic gardening, including the fertilizers and nutrients to grow everything from arugula to broccoli to marijuana. And Cook County sheriff's police routinely stake out the store and other retailers like it, surveying who buys what.

There's no evidence they're interested in the broccoli growers.

As the van pulled away, Donovan trailed it 17 miles to a one-story house with green aluminum siding on the 10000 block of South Exchange. South of the Skyway and walking distance from the Indiana state line, it's a quiet block of modest homes owned by city workers and Hammond casino employees.

From a safe distance, Donovan watched the van pull into a garage, and he was able to catch sight of the two men unloading the cargo. He then continued to follow the van as it left the house and drove another 11 miles to a condominium complex in Bridgeport.

Over the next few days, Donovan ran the van's license plate number and discovered it had been rented by 45-year-old Adrian Ortiz. He pulled a digital image of Ortiz from a driver's license database and recognized him as the stockier of the two men. Through a property search, Donovan discovered that Ortiz and a 47-year-old woman named Heidi Keller had purchased the house on Exchange six weeks earlier for $65,000.

At Donovan's behest, a Cook County grand jury subpoenaed records from ComEd to see how much power the property on South Exchange was consuming. As Donovan was well aware, the type of lighting rig necessary to grow broccoli—or pot—consumes an inordinate amount of energy. After comparing the bill to those of two other houses on the same block, Donovan found that electrical use in Ortiz's house had surged.

Donovan spent the next few weeks conducting surveillance on the house at different times of the day and night. Neighbors saw him and wondered why someone was sitting in a car on their street, but when they approached, Donovan drove off. He discovered that the basement windows of Ortiz's house had been covered with dark plastic—and through a gap he could see "an extremely bright light." He also repeatedly examined the garbage bins in the alley and found them empty—except once, when he discovered a single Jewel bag with a wet pot leaf inside.

With that leaf, authorities launched a case against Ortiz and Keller that would continue for more than two years.

Over the past year, the Reader has chronicled a number of problems with how marijuana laws are enforced in Chicago: they're applied differently among different racial groups, clog the courts, and consume millions of dollars and thousands of hours that could be used on other critical needs.

Acknowledging the costly inconsistencies, city officials recently joined dozens of suburbs and downstate towns in decriminalizing the possession of small amounts of pot. Meanwhile, federal law enforcement officials are focused on breaking up the often-violent criminal networks that supply area marijuana. At the top of the feds' list is the Mexico-based Sinaloa cartel, which—in a story that's commonly cited as evidence of the operation's reach—was found four years ago to be cultivating about 10,000 plants deep in a national forest in northern Wisconsin.

The thing is, the weed is going to come from somewhere—and nobody wants to get it from violent drug gangs. All of which raises an interesting question: What is a just way to deal with someone knowingly breaking the law by attempting to peaceably grow the marijuana that millions of ordinary and otherwise law-abiding people regularly consume?

In that context, it seems a bit surprising that the Cook County sheriff's department has in recent years poured resources into targeting a different kind of marijuana source than the gangs and cartels under investigation by the feds: grow houses.

Investigations of this kind are laborious, relying on stakeouts, surveillance, subpoenas, and search warrants, followed by dramatic arrests, colorful press releases, and photographs that make the news. The sheriff's police have even extended their investigations beyond the Cook County limits, to Romeoville, in Will County, and Chesterton, in northwest Indiana.