Piso was extremely well liked throughout Rome. He inherited from his father (never identified) connection with many distinguished families, and from his mother great wealth. Piso came from the ancient and noble house of Calpurnii^[1] and he distributed his great wealth among many beneficiaries of all Roman social classes. Among a wide range of interests, Piso sang on the tragic stage, wrote poetry, played an expert game of draughts, and owned a villa at Baiae.^[2]

Piso was tall, good-looking, affable, and an excellent orator and advocate in the courts. Despite these facts Piso's overall integrity was questionable. According to Tacitus, Piso used his eloquence to defend his fellow citizens and was generous and gracious in speech, but lacked earnestness and was overly ostentatious, while craving the sensual.^[1] In 40 AD, the emperor Caligula banished Piso from Rome after he took a fancy to Piso’s wife. Caligula forced Piso's wife to leave him, and then accused Piso of adultery with her in order to establish cause for banishment.^[3] Piso would return to Rome one year later after Caligula’s assassination.

In 41 AD, the emperor Claudius recalled Piso to Rome and made him his co-consul.^[4] Piso then became a powerful senator during the reign of Emperor Nero and in 65 AD led a secret initiative to replace Emperor Nero that became known as thePisonian Conspiracy.

Piso leveraged senatorial anger with the emperor Nero to gain power. Already in 62 AD, there had been talk among those of senatorial rank, in the nobility, and among the equites that Nero was ruining Rome.^[5] By 65 AD, the city had endured theGreat Fire of Rome and the persecution of the Christians, spurring groups of conspirators to come together under the leadership of Piso with the goal of killing the emperor Nero.

On April 19, 65 AD, the freedman Milichus betrayed Piso’s plot to kill the emperor^[5] and the conspirators were all arrested. In all, 19 were put to death and 13 exiled,^[5] revealing the massive scope of the conspiracy. Piso was ordered to commit suicide and so killed himself.

http://en.wikipedia.org/wiki/Gaius_Calpurnius_Piso

This coin from Nero shows:  This reverse type commemorates the protection of Nero from the Pisonian Conspiracy. Events of the years AD 64-65 defined the subsequent reputation of Nero as a cruel and self-indulgent ruler. In AD 64, a large section of central Rome burned; Nero's reputed singing of the destruction of Troy during the fire led to the later association of him "fiddling" as the city burned. Within the charred remains of the city's center, Nero constructed the Domus Aurea, or Golden House, so named because of the gilded tiles on its exterior. Nero's "excesses" resulted in a conspiracy to overthrow and replace him with Gaius Calpurnius Piso. Among the conspirators were many high-ranking members of Nero's court including Seneca the Younger, the poet Lucan, and Petronius, who called himself Nero's "arbiter of elegance." To Nero, the failure of a conspiracy made up of those so close to him could have been achieved only through divine intervention. As the king of the gods oversaw the security of the Roman state, Nero believed it was Jupiter the Guardian (Custos) who had saved him from harm. cngcoins.com

Based on this in-situ find, the villa has been identified as belonging to the powerful and wealthy aristocratic family Piso which organized a conspiracy against Emperor Nero. The plot was discovered and the family dispossessed. The villa, thus, came into the hands of the Emperor.

http://underwaterarchaeologicalparkbaia.blogspot.com/2009/12/pisonian-villa.html

Head of Lucius Calpurnius Piso Pontifex - from Pisoni's villa at Herculaneum - Naples, Archaeological Museum (photo from Karl)

FOR MORE ON THE PISONIAN VILLA AT HERCULANUEM :  For a better idea of how sumptuous the Villa at Baiae may have looked see my friends link at:  http://www.flickr.com/groups/historyantiquities/discuss/72157629129362872/#comment72157629912049557