Tiberius received Piso's son without either particular graciousness or particular disfavour, as if to show that he would remain unprejudiced until a public enquiry had been made into Germanicus' death.
Eventually
Piso
appeared at Rome with Plancina. They came sailing down
the Tiber and disembarked with a number of retainers at the tomb of Augustus, where they nearly created a riot by strutting with broad smiles through the hostile crowd which soon gathered, and stepping into a decorated carriage drawn by a pair of well-matched white French cobs which was waiting for them on the Flaminian road. Piso had a house overlooking the Market Place and this was decorated too.
He invited all his friends and relations to a banquet celebrating his return and made a great deal of disturbance: merely to show the people of Rome that he was not afraid of them and that he counted on the support of Tiberius and Livia.
Tiberius had planned for Piso to be prosecuted in the ordinary Criminal Court by a certain senator who could be trusted to do it so clumsily, contradicting himself and neglecting to produce proper evidence in support of his charges, that the proceedings could only end in an acquittal. But Germanicus' friends, especially the three senators who had been on his staff in Syria and had returned with Agrippina, opposed Tiberius' choice. Tiberius was forced in the end to judge the case himself, and in the Senate too, where Germanicus' friends could count on all the support they needed. The Senate had voted a number of exceptional honours to Germanicus' memory--cenotaphs, memorial arches, semi-divine rites--which Tiberius had not dared to veto.
Castor now returned once more from the Danube and, though an ovation
[or lesser triumph] had been decreed him for his management of the Maroboduus affair, he entered the City on foot as a private citizen instead of in a war-chariot with a chaplet on his head. After visiting his father he went straight to Agrippina and swore to her that she could count on him to see that justice was done.
Piso asked four senators to defend him; three of them excused themselves on the ground of sickness or incapacity; the fourth, Gallus, said that he never defended anyone on a murder charge of which he seemed guilty unless there was at least a chance of pleasing the Imperial family. Calpurnius Piso, though he had not attended his uncle's banquet, volunteered to defend him for the honour of the family, and three others afterwards joined him because they were sure that Tiberius would acquit Piso, whatever the evidence, and that they would later be rewarded for their part in the trial. Piso was pleased to be judged by Tiberius himself, because Sejanus had assured him that it would be all properly managed, that Tiberius would pretend to be very severe but finally adjourn the court sine die for fresh evidence. Martina, the principal witness, had already been put out of the way--smothered by Sejanus' agents--and the prosecutors now had a poor case.
Two days only were allowed for the prosecution, and the man who had been originally commissioned to bungle it for Piso's benefit came forward and did his best to talk the time out by bringing stale charges against him of misgovernment and corruption in Spain under Augustus. Tiberius let him continue with this irrelevant matter for some hours, until the Senate, by scuffling feet, coughing and clattering writing-tablets together, warned him that the principal witnesses must be heard or there would be trouble.
Germanicus' four friends had their case well prepared and each in turn rose and testified to Piso's corruption of military discipline in Syria, his insulting behaviour to Germanicus and themselves, his disobedience of orders, his intrigues with Vonones, his oppression of the provincials.
They accused him of murdering Germanicus by poison and witchcraft, of offering thanksgiving sacrifices at his death, and finally of having made an armed attack on the Province with private forces illegally raised.
Piso did not deny the charges of corrupting military discipline, of insulting and disobeying Germanicus, or of oppressing the provincials; he merely said that they were exaggerated. But he indignantly denied the charge of poison and witchcraft. The accusers did not mention the supernatural events at Antioch for fear of encouraging sceptical laughter, nor could they accuse Piso of interfering with Germanicus' household servants and slaves, because it bad already been shown that they had nothing to do with the murder. So Piso was accused of poisoning Germanicus' food while he sat next to him at a banquet in Germanicus'
own house. Piso ridiculed this charge: how could he possibly have done such a thing without someone noticing it, when the whole table, not to mention the waiters, were watching every movement he made? By magic perhaps?
He had a bundle of letters in his hand which everyone knew, by the size and colour and the way they were tied, were from Tiberius. Germanicus' friends moved that any instructions that Piso had been sent from Rome should be read.
Piso refused to read the letters on the ground that they were sealed as with the Sphinx seal [originally Augustus'], which made them "secret and confidential": it would be treasonable to read them. Tiberius ruled against the motion, saying that it would be a waste of time to read the letters, which contained nothing of importance. The Senate could not press the point. Piso handed the letters to Tiberius as a sign that he trusted him to save his life.
Angry noises were now heard from the crowd outside, which was being kept informed of the progress of the trial, and a man with a huge raucous voice shouted through a window: "He may escape you, my Lords, but he won't escape us!" A messenger came to tell Tiberius that some statues of Piso had been seized by the crowd and were being dragged to the Wailing Stairs to be broken up. The Wailing Stairs were a flight of steps at the foot of the Capitoline Hill where the corpses of criminals were customarily exposed before being dragged by a hook in the throat to the Tiber and thrown in. Tiberius ordered the statues to be rescued and replaced on their pedestals. But he complained that he could not continue to judge a case under such conditions and adjourned it until the evening. Piso was conveyed away under escort. Plancina, who had hitherto boasted that she would share her husband's fate whatever it might be, and if necessary die with him, now grew alarmed. She decided to make a separate defence and counted on Livia, with whom she had been on intimate terms, to get her off. Piso knew nothing of this treachery. When the trial was resumed Tiberius gave him no sign of sympathy, and though he told the accusers that they should have provided more conclusive evidence of poisoning, he warned Piso that his armed attempt to win back his province could never be forgiven. At home that evening Piso shut himself in his room and was found the next morning stabbed to death with his sword beside him.
It was not, as a matter of fact, suicide.
For Piso had retained the most incriminating letter of all, one written to him by Livia but in the names of Tiberius and herself, and not stamped with the Sphinx seal [which Tiberius reserved for his own use]. He told Plancina to bargain for their lives with it. Plancina went to Livia. Livia told her to wait while she consulted Tiberius.
Livia and Tiberius then had their first quarrel. Tiberius was furious with Livia for having written the letter, and Livia said that it was his own fault for not allowing her to use the Sphinx seal and complained that he had been behaving very insolently to her lately. Tiberius asked, who was Emperor, he or she? Livia said that if he was, it was by her contrivance and that it was foolish of him to be rude to her, because as she had found means to make him, so she could find means to break him. She took a letter from her purse and began reading it: it was an old letter written to her by Augustus during Tiberius' absence in Rhodes, accusing him of treachery, cruelty and bestiality and saying that if he were not her son he would not live another day. "This is only a copy," she said. "But I have the original in safe keeping. It's only one of many letters in the same strain.