The fire investigation into the New London fire that killed former Zappos CEO Tony Hsieh is now complete. New London’s Fire Marshal’s Office released the report Tuesday morning, saying that the investigation team has developed four hypotheses as to what caused the fire and how human factors could have also contributed to Hsieh’s death. The office of the state medical examiner said Hsieh died of smoke inhalation and his death was ruled an accident. According to the report, the first hypothesis is that “the portable propane heater came into direct contact or into proximity of the heating elements with the nearby combustibles resulting in a fire.” Another hypothesis is that a “carelessly discarded smoking material (either cigarettes or marijuana) is the cause of the fire.”