Trusting no one, he believed he was under constant surveillance and described a situation where he met a woman at a safe house. The meeting came right after he and other officers had been warned that the cartels were using women to try to get agents into Mexico in order to kill them.
When the first person he met at a safe house was a woman, he was terrified. The cartel told him the woman was there for his "personal enjoyment," but he suspected the real purposed was to get him naked so that they could see that he was not wired.
He can't stop thinking about what he has done and can't stop worrying about the cartel, even behind bars.
"I worry a lot because I know [their] method of operation and in what areas [they operate]," the guard wrote. "In other words, I believe that they think that I know too much."
He isn't just afraid for himself.
"I worry about my family because they are living in border towns and in Mexico," he said. "I fear for their lives because I believe that those people are just waiting for me to say the wrong thing about them or someone in particular."
The Mexican drug cartel industry has an estimated worth of more than $15 billion and continues to grow. Violence has escalated in the industry and battles involving automatic weapons and grenades are common. Over 34,000 people have been killed in Mexican drug wars over the past four years.
In a disturbing trend, new figures show 122 current or former U.S. federal agents and employees of the Customs and Border Protection agency have been arrested or indicted for corruption since October 2004. It's not just for money, some agents are accepting payment from the cartels in the form of sexual favors.
Just last week, a police officer, a state trooper and three TSA officers in Florida and Connecticut were among 20 arrested for allegedly running an interstate drug ring. "
"It will get worse before it gets better," the former agent predicted.
Even though the agent describes prison life as "a terrible experience," he believes he did the best he could for the circumstances he was in.
"I knew that what I was doing was wrong. But, at the time, I thought I had no other options," he said. "It's easy to find an answer right now, but back then...it was a nightmare."