SAO PAULO, Brazil — A new autopsy has determined that President Salvador Allende of Chile killed himself with an assault rifle, Chilean officials said Tuesday, dispelling doubts that have persisted for 37 years about the exact circumstances of his death, including whether troops storming the presidential palace had murdered him.

The forensic analysis, overseen by a team of Chilean and international experts, did not find any evidence that others were involved in Allende’s death, concluding that the head injuries he sustained were consistent with bullets fired from a single AK-47 assault rifle.

Leftist supporters like Fidel Castro had declared that Allende died in a gun battle on Sept. 11, 1973, the day of the coup.