The issue was it would take two years to get to trial, during which he'd be incarcerated anyway and they offered him a three year plea bargain. Unfortunately, it didn't turn out to be a "bargain."

By the way, in case it wasn't clear; I liked and recommend this movie. I told my wife all about it today and she found it hard to believe and wanted to know if it's based on a true story. I'd guess there are more than a few true stories like this one...