A 72-year-old Dartmouth man has been found guilty of sexually assaulting a developmentally disabled Berkshire County woman. Richard St. Louis was found guilty Tuesday of charges including four counts of indecent assault and battery on a person with intellectual disabilities. He was acquitted of one indecent assault and battery charge. He was sentenced to five years in prison. Prosecutors said St. Louis molested the now 24-year-old woman with the problem-solving skills of a 4-year-old child between January 2008 and September 2011 in Hancock, where he went to hunt.