He committed suicide in exile at Rhodes after being proscribed by Lucius Cornelius Sulla shortly after the latter's victory in the civil war.

[3] Although the Senate vigorously tried to obtain his acquittal and he was defended by Lucius Licinius Crassus, Norbanus managed to secure Caepio's conviction.

In 101 BC, Norbanus served as quaestor under Marcus Antonius, grandfather of the triumvir Mark Antony, in his campaign against the pirates in Cilicia.

[4] In 94 BC, Norbanus was accused of minuta maiestas (treason) under the Lex Appuleia by Publius Sulpicius Rufus on account of the disturbances that had taken place at the trial of Caepio, but the eloquence of Marcus Antonius secured his acquittal.

[12] Although Norbanus was helped by Quintus Sertorius, they were defeated by Sulla at the Battle of Mount Tifata,[13] losing around 6,000 men in the process.