Westerberg was arrested for selling illegal signal descramblers for satellite TV. These boxes made it possible for people to watch satellite television without paying for a subscription. Westerberg was caught and sentenced to prison for four months.

Westerberg lived in Carthage, South Dakota and earned a living as a traveling grain harvester. He and his crew would travel the plains, harvesting wheat and barley. Westerberg met McCandless when he picked him up hitchhiking outside of Cut Bank, Montana. Westerberg and McCandless hit it off, and McCandless worked at a grain elevator Westerberg owned for a time. When Westerberg was convicted, the work at the elevator dried up, and McCandless moved on.

McCandless's link with Westerberg proved to be durable, however. McCandless was always finding surrogate families during his travels, and it's clear he considered Westerberg's Carthage home, where he lived with several of his crew members, a kind of refuge. Carthage itself was a small, out of the way place, and its obscurity suited McCandless well. Westerberg remembered McCandless as outgoing, smart, and hardworking—almost to a fault. Like other outdoor adventurers Krakauer mentions (Ed Abbey, Everett Reuss), McCandless had a need for human companionship that often was hard for him to square with his love of the wilderness. This partly explains why McCandless often would send post cards to Westerberg and used Westerberg's Carthage address as a home address.

Like most real people, Wayne Westerberg was a mix of conflicting characteristics. On the down side, he was arrested for his participation in a scheme to create and market black boxes, illegal devices that allowed people to download satellite television from cable channels without paying for the content. Westerberg was caught in an FBI sting operation and convicted for his part in this scheme, ending up with a felony conviction. He began a four-month jail term only two weeks after Chris arrived in Carthage. Up to that time, Chris had worked for Wayne on his combine crew, renting a room in a house Wayne owned.

Westerberg was an important mentor to Chris McCandless. In the opening of Krakauer's book, Krakauer quotes from a postcard that Chris sent to Westerberg on the eve of his fateful journey to Alaska. Chris wrote,

If this adventure proves fatal and you don’t ever hear from me again, I want you to know you're a great man.

Chris was able to see past the mistake Westerberg had made to appreciate the whole person. As with so many people, Wayne's great strength was also his weakness. Westerberg's strength was his high-energy curiosity and zest for living, which meant he had hand in any number of projects. Krakauer refers to him as a Renaissance man, meaning he knew a little bit about a lot of subjects. This high-energy curiosity drove him to reach out to and bond with Chris but also led to his unfortunate, if brief, foray into crime.

Wayne Westerberg is a grain elevator operator who picks up the broke and hungry hitchhiker Chris McCandless (going by the name "Alex" at the time) on the drive to Carthage, South Dakota. After three days of working on Westerberg's crew, Wayne offers Chris a job if he ever needs one in the future. Chris eventually returns to Carthage and forges a family-like bond with Wayne, but only two weeks after he has begun this work, Wayne is arrested for pirating satellite television service through the construction of black boxes, a fate which is described in the book as follows:

Westerberg had been drawn into a scheme to build and sell "black boxes," which illegally unscramble satellite-television transmissions, allowing people to watch encrypted cable programming without paying for it. The FBI caught wind of this, set up a sting, and arrested Westerberg. Contrite, he copped a plea to a single felony count and on October 10, 1990, some two weeks after McCandless arrived in Carthage, began serving a four-month sentence in Sioux Falls. 

Without steady work to keep him in one place, Chris decided to go back on the road. However, before leaving Carthage, he gave Wayne his 1942 edition of Tolstoy's War and Peace with an inscription that read, "Transferred to Wayne Westerberg from Alexander. October, 1990. Listen to Pierre." Chris continued to periodically keep in touch with Wayne, and Wayne was the recipient of the final postcard Chris sent before his death.

Chris McCandless's boss at this point in the text was Wayne Westerberg.  Westerberg owned a grain elevator in Carthage, South Dakota.  When he is not there, Westerberg operates a custom combine crew that follows the harvest every summer from Texas to Canada.  The text says that Westerberg is quite adept at just about anything that he does.  He is an actual "jack of all trades."  

A Renaissance man of the plains, he is a farmer, welder, businessman, machinist, ace mechanic, commodities speculator, licensed airplane pilot, computer programmer, electronics troubleshooter, video-game repairman.

It is probably because of those diverse skills that he got pulled into a scheme to build "black boxes."  Those boxes are devices that can find and unscramble the satellite signal being sent out to televisions.  In other words, if you have a black box, you get free satellite television.  The FBI deems that practice as illegal, so the FBI set up a sting to capture and arrest Westerberg.  He confessed to a single felony and was forced to serve a four month sentence.  That occurred only a few weeks after McCandless arrived, so without Westerberg in Carthage, McCandless returned to his nomadic lifestyle.  

"Black boxes" are devices which unscramble satellite-television transmissions illegally.  They allow people to watch encrypted cable programming without paying for it.  Chris's boss at the wheat fields, Wayne Westerberg, had been in on a scheme to manufacture and sell these boxes, and was arrested in an FBI sting.  Westerberg pleaded guilty to a single felony count, and served a four-month sentence in prison (Chapter 3).