[1] Suetonius describes him as "a lecherous old spendthrift" and states that the emperor Augustus had expelled him from the Senate for his shameful behavior.
The first is in his account of AD 21, when Gallus is reported to have made a speech in the Senate complaining that "the vilest wretches" would slander "respectable citizens" then escape punishment for their harm by clutching a statue of the emperor; in his speech, Gallus mentions specifically one Annia Rufilla.
His speech provoked a response from the assembled body that forced Drusus the Younger to order Annia Rufilla summoned, convicted, and confined to the common prison.
Tiberius prompted Gallus to read to the Senate a letter he sent the emperor, in which he accused the ex-praetor Quintus Servaeus and the equestrian Minucius Thermus of being supporters of the feared but now dead praetorian prefect.
In response to Gallus' prosecution, the two then offered up Julius Africanus and Seius Quadratus as other associates of Sejanus to avoid proscription.