''SHACKLED by a heavy burden, filled with guilt and shame!'' Jack Black joyfully belts out an old gospel song mid-interview. One of Hollywood's favourite contemporary comedians, he has spread amiable mayhem across films such as Tropic Thunder, Shallow Hal and Kung Fu Panda.
Black takes the title role as a flamboyant Texan undertaker in the new dark comedy Bernie, from Richard Linklater (Slacker, Dazed & Confused, Fast Food Nation). Black and Linklater reunited almost a decade after making School of Rock for the mocku-drama retelling of one seriously peculiar real-life murder case. Crucial to the hilarity is the collection of quirks - based on factual research - that Black brings to his portrayal of killer Bernie Tiede.
''Bernie really did lead his congregation in gospel songs,'' Black says. ''Those were real hymns! They have a strange sexual resonance and a grim foreboding. The walls are closing in; Bernie feels he's about to be found out.''
Bernie's macabre secret is the corpse of an elderly millionaire, Marjorie Nugent, hidden in his freezer. Marjorie is played by the legendary Shirley MacLaine, a co-star Black was thrilled to work opposite.
''Man, she's the real deal, and she's still got it!'' he says.
Bernie was adored by the townsfolk of Carthage, Texas. Kind, polite, cheerful and impeccably groomed, he was a friend and confidant to grieving widows and a model funeral director. Bernie's involvement in the church, his generosity and skill at needlepoint made him a highly sought companion to older women.
Marjorie, on the other hand, was cruel, racist and foul-tempered. The citizens of Carthage were puzzled when Bernie shacked up with an obnoxious woman almost 50 years his senior.
When he was slowly abused into submission, things turned nasty. '''Why didn't you just leave?' I felt like this was the big question the audience would be asking,'' says Black, so he travelled to a Texan jail to put his inquiry to the real Bernie Tiede. ''I wanted to get a better idea of who he was and ask him about his relationship with Marjorie,'' he says. ''It's tricky and really weird to ask people super-personal questions … in jail.
''Bernie didn't have a release valve for his anger and he snapped; a classic case of temporary insanity. He definitely deserved to do time, it was a horrible crime, but he did not get a fair trial.''
The district attorney, Danny ''Buck'' Davidson, is played with evil glee by Matthew McConaughey.
''Buck was able to flip the story and get a much more severe sentence,'' Black says.
A great deal of the charm of Bernie lies in the style in which Linklater chose to tell the story.
Apart from a small core cast, the bizarre tale is told in interviews - rife with gossip - with the actual townsfolk of Carthage.
''[Linklater] felt that was a compelling part of the story,'' Black says. ''That no one in that small town believed that Bernie would be capable of something like that.''
Behind bars for life, Tiede was delighted to be a part of the film.
Black is still incredulous. ''In the prison workshop, Bernie was working on beautiful memorials for people that had recently passed away. I know there's still a lot of love for Bernie in Carthage. But, seriously, a dead body in your freezer for nine months?!''
Bernie opens on Thursday.