The man, who has not been named by police, was set to begin serving a prison sentence of three and half years on Monday. According to the Rhein-Zeitung (RZ) newspaper, he had been convicted in 2010 of abusing a four-year-old child beginning in 1986 and lasting into late 1993.
The man left a suicide note and doused himself with a flammable liquid before setting himself alight on Monday afternoon. Although he was taken to a nearby emergency clinic, he died overnight.
Throughout his trial, he expressed outrage at the charges against him and accused his victim of fantasizing, the paper reported.
He admitted an attraction to children but denied ever having had sex with them. The man had also spent time in prison decades ago for abusing a child, although he continued to maintain his innocence, according to the newspaper.
It's not clear why the man killed himself, although a court employee reported that he had wanted to protest against his conviction.