A federal jury found Thomas Zajac guilty on six felony charges for the 2006 attack.
When Zajac got angry about some I-PASS fines, he poured glue into an Illinois tollway coin basket. Authorities said that was just one example of a man who always had to even the score. But Zajac's retaliation began to get more serious -- not just pranks -- authorities say he started to use explosives.
The DuPage County bomb squad had to blow up one device that investigators say Zajac planted on Main Street in Downers Grove in August 2004.
It was a bomb in a trash can near the Hinsdale train station in September of 2006. And then two weeks later a pipe bomb blew up inside the Salt Lake City main library.
On Monday, a federal jury convicted the 57-year-old Zajac of using a destructive device in a crime of violence and five other felonies that could keep him locked up for the rest of his life.
He didn't admit to anything in court, in keeping with his position during a jailhouse interview the I-Team did with him a few years ago. "I had nothing to do with the event," he said then.
Fingerprints linked Zajac to the Salt Lake bombing. Letters to police in Hinsdale and Downers Grove connected him to those crimes for which he will soon stand trial.
From the time he was arrested in Downers Grove, investigators believed that on each occasion a bomb was placed Zajac was trying to avenge something that happened during encounters that he or his relatives had with local authorities. That included his son's drunken driving arrest and a domestic incident.
"I don't have bad feelings towards the police in Downers Grove or in Hinsdale, certainly no reason to be spiteful towards the police," said Zajac in 2006.
Zajac had a temper outburst in federal court when his own lawyers suggested that his son had more of a motive for the bombings than he did. According to the prosecutor, Zajac was a bitter and angry man with ample motivation.
The jury didn't buy into any of Zajac's excuses or antics, convicting him on all the major counts.