In January 897, workmen inside St. Peter’s Basilica pried open a stone sarcophagus, lifted out what remained of Pope Formosus, and carried him across Rome to stand trial. Formosus had been dead for nine months. His body was dressed in the full vestments of the papacy, propped upright on a throne in the council hall of the Lateran Palace, and a young deacon was placed beside him with instructions to answer the charges on the corpse’s behalf.

The judge was the living pope, Stephen VI, who screamed the accusations one after another: that Formosus had illegally moved from the bishopric of Porto to the see of Rome, that he had broken the oath he swore never to return to the city, that he had been ambitious and perjured. The bishops of the Roman church sat on their benches in January 897 and watched a dead man cross-examined by a living one. The corpse was found guilty. The trial came to be known as the Cadaver Synod, and it was the darkest single episode in the history of the papacy.

Its roots ran deep through the political wreckage of the late ninth century. Formosus, born around 816, had risen through the Roman church as a talented and deeply respected figure. As cardinal bishop of Porto, he had impressed the Bulgarian khan so completely that the khan asked to have him as archbishop; Rome refused. Later, after a falling out with Pope John VIII, Formosus fled the city, was excommunicated, and in 878 knelt before a council, swore he would never return to Rome or exercise his ministry again, and was restored only as a layman.

The oath haunted him for the rest of his life. In 891, Formosus was elected pope anyway, at about seventy-five years old. He inherited a poisoned situation. The Carolingian Empire was collapsing, and Italy’s warlords were fighting over the imperial crown, which only the pope could grant.

The Spoleto dynasty, led by Duke Guy III and his formidable widow Ageltrude, had already extracted the imperial title and wanted it secured for their son Lambert. Formosus crowned the boy co-emperor in 892, but he hated doing it. He had been elected to save the church, and instead he sat in a cage of Spoleto power. So he reached across the Alps to Arnulf of Carinthia, the last credible Carolingian, and urged him to march on Rome and take the crown.

Arnulf came in 896, stormed the city, and Formosus crowned him emperor and declared Lambert deposed. The gamble seemed to have worked. Then Arnulf collapsed on the road to Spoleto, half paralyzed, and was carried home over the Alps, never to return. Ageltrude and Lambert were alive, free, and furious, with their army intact days from Rome.

Six weeks after his triumph, on April 4, 896, Formosus died, probably of age and strain, though rumors of poison never died. He was buried with full honors in St. Peter’s. His tomb did not hold him long.

Ageltrude and Lambert were back in Rome by the beginning of 897, and Stephen VI, their candidate, sat on the papal throne. Stephen had his own reason to hate Formosus: the dead pope had consecrated him bishop of Anagni years before, and under canon law, a bishop who moved from one see to another forfeited his rank. Stephen had moved from Anagni to Rome, the same crime he intended to prosecute. If Formosus had never validly been pope, then his consecrations were void, and Stephen had never been bishop of Anagni at all.

The verdict on the corpse would retroactively cleanse the judge. The trial was a masterwork of ritual desecration. The body was robed in full papal vestments and propped on a throne. The charges were read.

The deacon beside the corpse answered as best a terrified boy could. Stephen paced the hall and screamed at the dead man: Why did you usurp the Roman see? The verdict came as planned: guilty on all counts. Formosus’s election was declared void from the beginning, and every act of his five-year pontificate was annulled.

All his ordinations were invalidated, which meant a generation of priests, bishops, and their sacraments were suddenly void as well. Stephen demanded written confessions from clergy ordained by Formosus, forcing men to sign away their own orders. Then they turned to the body. The vestments were stripped off.

The three fingers of the right hand, the fingers used for blessing and consecration, were cut off. The corpse was dressed in layman’s clothes and buried in a cemetery for foreigners. Within days it was dug up again, dragged through the streets, and thrown into the Tiber. A chronicler in a monastery north of the Alps wrote that blood flowed from its mouth as it was dragged, though such a thing was physically impossible; the people who heard of it remembered it that way anyway.

The city was not quiet. An earthquake struck Rome, and the Lateran Basilica, the very hall where the trial had been held, collapsed from the papal altar to the doors. Romans took it as a sign from God. Meanwhile, the Tiber returned the body.

Fishermen or a guided monk pulled it from the shallows downstream, and it was hidden and kept safe. Stories began to spread that the corpse had been found strangely preserved, and that the images of the saints in St. Peter’s bowed as it was carried in. Whatever the truth, Rome had decided it was on the dead man’s side.

By the summer of 897, Stephen VI was exposed. The Spoleto forces who had protected him had left Rome to put down revolts elsewhere, and the city rose against him. He was dragged from his palace, stripped of the papal insignia, dressed in a monk’s habit, and thrown in chains into a cell. There he was strangled.

His body was buried in St. Peter’s, in the portico among the popes, in the very church from which he had ordered a corpse torn. Nobody dug him up. Nobody tried him.

What followed was a decade of chaos. In eight years, Rome went through roughly nine popes. Theodore II, elected in December 897, reigned twenty days and in that time annulled the Cadaver Synod, restored Formosus’s acts and ordinations, and gave the body a proper funeral, dressing it once more in papal vestments and laying it back in its tomb. John IX followed, burned the official transcript of the trial, excommunicated the unrepentant judges, and passed a law banning the trial of any dead person forever.

A council at Ravenna confirmed all of it, and Lambert of Spoleto, the supposed beneficiary, approved the annulment in person. Then in 904, Sergius III took Rome with armed force and took the papacy. He was a veteran of the Cadaver Synod, one of the bishops who had sat in judgment, and he had never repented. He reaffirmed the verdicts against Formosus, demanded reordination of the clergy, and effectively revived the whole nightmare.

His reign opened the era historians later called the dark age of the papacy, a period of sixty years in which the family of the noblewoman Marozia made and unmade popes at will. Under one account, Marozia herself had been Sergius’s mistress and bore him a son, who later became Pope John XI. The papacy had become a knife passed around a table of enemies, and every man who picked it up knew he was likely holding his own murder weapon. Stephen VI’s name never came to rest.

He appears in different records as Stephen VI or Stephen VII, depending on whether scribes counted a pope who died within days of his election. His monument, commissioned by Sergius, called Formosus “filth” and boasted of the trial, and recorded Stephen’s own end with a frankness that still stops historians: bound with chains, strangled in the depths of the prison. The marble itself is gone, preserved only as a transcription by Renaissance antiquarians. For Formosus, no grand restoration ever came.

He remains in every official list of legitimate popes, his acts treated as valid, his ordinations honored. But he was never canonized, and no pope has ever taken his name again. His tomb was lost in the rebuilding of St. Peter’s centuries later, and his bones, if they survive at all, lie unlabeled in the common papal crypt.

Of all the ground in this story, the one place no one will ever find is the stretch of riverbank where a fisherman lifted a mutilated body from the shallows and chose to treat it as a man instead of refuse. That act, like the trial itself, has never been forgotten, though no marker records it.