Complex sentence: Little is known about Riddick's childhood, save that he had no formal education and seems to have been in trouble with the law from an early age, claiming to have been "educated" in the penal system.
Split into simpler sentences: Little is known about Riddick's childhood, save that he had no formal education and seemed to have been in trouble with the law from an early age. He claims to have been "educated" in the penal system.