VIDEO: Officials in Berkshire County believe a house fire in Sheffield was set intentionally by a man they say killed his family and himself. According to Berkshire County District Attorney Andrea Harrington, Luke Karpinski killed his wife and three children before intentionally setting the family's home on fire, then committing suicide. Karpinski's 41-year old wife Justine Wilbur's body was found on the first floor of the home with a traumatic injury, that the DA says seems to have happened before the fire on Home Road started last Wednesday morning. The bodies of Karpinski and his 7-year old twin daughters and 3-year-old son were later found on the upper floor of the home. Investigators found evidence of an accelerant in different parts of the home, including two 20-pound propane tanks on the upper floor.