Investigators are looking for the cause of a weekend fire that killed a man in Appleton. Officials say the man’s house was fully engulfed in flames when firefighters arrived Saturday. A next-door neighbor spotted the flames and called 911. Firefighters were able to bring the blaze under control in about 30 minutes and found the victim once the fire was extinguished. Fire officials say the house is considered a total loss. The state fire marshal’s office is investigating.