On a muggy autumn morning four decades ago, a car exploded in Washington. It had motored along Massachusetts Avenue NW, rounding the bend at Sheridan Circle, when a remote-controlled bomb taped beneath the vehicle was triggered.

A driver in a car nearby would later describe the fiery impact of the blast: “I saw an automobile actually coming down out of the air.”

The smoldering wreck lurched to a halt in front of the Romanian Embassy, its windows blown open and entire floor panel gone. A police officer who arrived on the scene remembered welling up with nausea. There was blood and debris everywhere and a human foot in the roadway. A fatally wounded man lay on the pavement; his legs were missing from above the knees.

This was Orlando Letelier, a 44-year-old former Chilean diplomat who had been driving to work at a D.C. think tank along with his colleague, Ronni Moffitt, 25, and her husband, Michael.

Letelier died within minutes. Shrapnel had pierced Ronni Moffitt’s throat, and she drowned in her own blood a half-hour later. Michael, who had been sitting in the back seat, tumbled out largely unscathed. He was beside himself in grief and shock.

“Assassins, fascists!” he exclaimed amid the carnage.

They were victims of a brazen, perhaps unprecedented plot, the target of a foreign regime that had sent agents into the United States to kill Letelier. Here was a case of state-sponsored terrorism in the heart of the American capital. Only in this instance, the state was a close Washington ally in the Cold War.