On May 5, two female FBI agents approached a farmhouse in Salem carrying a bottle of sparkling water, a potted plant and a greeting card from the local chamber of commerce.

When a Mexican woman answered the door, the agents introduced themselves as members of the local Welcome Wagon. The woman, who identified herself only as Ana, spoke little English and seemed eager for her visitors to leave.

Special Agent Michael Holeman, who was overseeing the investigation, later wrote in an affidavit that he believed the woman was "being held against her will and forced to grow marijuana."

He had reasons for his suspicions.

In November 2005, another Mexican woman named Mayra Martina Hernandez-Vargas had told the FBI that the owner of the farmhouse, Ramon Lopez-Montanez, had kidnapped her in Mexico, subjected her to physical and sexual abuse and brought her to Lincoln County, Ore., where he forced her to tend to one of his marijuana-growing operations.

By the time the undercover "Welcome Wagon" arrived on the farmhouse doorstep, Lopez-Montanez, who lived elsewhere, had become the object of a sophisticated investigation that has culminated in what federal officials say is Oregon's first prosecution for human trafficking (see "Captive Labor," WW, June 14, 2006).

Months earlier, an agent had planted a global-positioning tracker on Lopez-Montanez's 1998 Dodge truck, allowing the FBI to track his movements between various homes where he was suspected of growing marijuana crops and big-box store parking lots where he may have sold the harvests.

In a helicopter equipped with infrared technology, an agent had identified hot spots indicating a possible indoor growing operation at the Salem farmhouse Lopez-Montanez bought for $300,000 the previous fall.

The FBI had collected unusually high meter readings from the electric company and confirmed that Rusticos de Mexico, an Oregon business registered in the name of Lopez-Montanez and his American wife, Dana Montanez, had neither a brick-and-mortar headquarters nor a working telephone.

Meanwhile, his original accuser, Hernandez-Vargas, had moved out of the home in Otis, Ore., where she said she'd been held for three years.

According to neighbors, 20-year-old Hernandez-Vargas had moved across the street with the "concerned neighbor" who originally contacted the FBI about her plight. Neighbor Martha Cooksey says the couple (neither of whom could be reached for comment) is now married. Immigration officials have granted Hernandez-Vargas the right to stay in this country legally, and given her a work permit, medical services, counseling and $1,500 cash.

Less than three weeks after the May 5 Welcome Wagon visit, the FBI and local police executed search warrants in Salem and Otis on May 23, arresting Lopez-Montanez and two alleged co-conspirators, and seizing guns, marijuana and growing equipment.

Although the arrest marks Oregon's first human-trafficking prosecution, 248 defendants have been targeted nationwide since the enactment in 2000 of a federal law that extends additional protections to victims who are willing to testify. In recent months, Oregon's U.S. Attorney's office also has been encouraging local prosecutors to look out for potential cases.

Nonetheless, there is widespread debate over the size of the problem. The federal government estimates between 14,500 and 17,500 trafficking victims are brought into this country each year. A recent Justice Department report, however, cautions that those numbers may be inflated.

Emerging details about the mini-cartel allegedly run by Lopez-Montanez and his brothers say a lot about the ambiguous situation of immigrants who do the grunt work in Oregon's drug industry.

Ana Aguilar-Torres, who greeted undercover agents May 5 at the Salem farmhouse, was also arrested May 23. While agents believe she was also a victim, Aguilar-Torres told the FBI she was in love with Lopez-Montanez, who paid her $2,000 a month to tend his crops. She has since been charged with conspiracy to distribute and manufacture marijuana and possession of a firearm by an illegal alien.

Salem Police Sgt. Pat Garrett says the low-level drug dealers he meets often fall into a gray area between slavery and something less explicit.

"What we do see a lot of is, people get recruited and they voluntarily agree to do it, kind of [like] an indentured servant," Garrett says.

The problems start, he says, when they decide they want to get out of it, but "they come from the same town as the guy who recruited them, and they're afraid for their family."

The bosses' implied message, Garrett says, goes something like this: "We're not going to go after you, but we can certainly harm your family members in Mexico."

"That's the kind of threat they use to keep people in line," he says. "It's a known thing."

Police may soon encounter more illegal immigrants stuck along the spectrum of victimization in the drug business; marijuana cultivation, already a cash crop in Oregon, is growing, according to drug enforcement agencies.

In 2005, Oregon ranked seventh in the nation for marijuana plants seized, below top-ranked California and sixth-ranked Washington. Federal marijuana seizures here have increased more than 300-fold in recent years, rising from 19.5 kilograms in 2002 to 7,146.4 kilograms in 2005.

Ken McGee, the DEA's assistant special agent in charge for Oregon, says he's not entirely sure why the numbers have grown so fast. Asked if increased enforcement plays a role, McGee would only say his budget has not decreased in recent years.

He points to Mexican cartels and the state's low penalties for those convicted of selling weed. He puts the most blame on Oregon's legalization of medical marijuana in 1999, under which more than 16,000 patients and caretakers have the right to grow their own. In fact, Lopez-Montanez's wife carries a state-issued medical marijuana card.

Garrett says Mexican cartels are moving into Oregon at a faster pace, although their presence is nothing new. They have refined methods of outdoor cultivation, he says, building high-tech irrigation systems to grow thousands of plants on public forest land. In downtown Salem on weekend nights, Garrett says he has spotted suspected drug bosses in snakeskin boots and white cowboy hats lined up outside clubs blaring mariachi music.

Lopez-Montanez, who the FBI says grew hundreds, not thousands, of plants, does not fit the bill of a high roller. He appeared in court with scraggly salt-and-pepper hair and glasses.

Neighbor Steven Miller describes Lopez-Montanez as "clean, neat and very polite." He has a teenage son and daughter, Miller says, and behaves like a normal working-class dad. When the FBI arrived, according to an affidavit, the 13-year-old son said aloud, "Daddy has never worked."

Lopez-Montanez, now jailed in federal prison in Sheridan, has entered pleas of not guilty.

Read "

," the first part of this series.