He became especially close to a not so well-liked wealthy widow, played by Shirley MacLaine.
"When Shirley comes to the set, she comes with her legend. But also an incredible energy," said Black, who added that working with MacLaine was a joy.
Bernie loved the affluent lifestyle he was afforded through this relationship; what he didn't love was his new companion's controlling ways.
So one day he snapped, shot her and hid the body in a freezer for nine months.
Black had the opportunity to meet the real Bernie, who is in prison.
"It helped immensely just to hear him talk, and to watch his behavior, and to ask him a few questions about his life, those things are big," he said.
"Bernie" director Richard Linklater utilized many real-life residents of East Texas to help tell the story. For the most part, the neighbors didn't fault Bernie for his actions.
He also gave his stars room to play.
"That's what was great about Rick he let us do our improv," said MacLaine. "God, I don't know what would have happened if I'd been with, who was that terrible comedian in Vegas?" she asked Black, who joked his way out of naming any one comedian.
"Bernie" also stars Matthew McConaghey as the town district attorney. His mom also has a part in the film as one of the "real" people who is a town gossip.