sejanus had served the imperial family for almost twenty years when he became praetorian prefect in ad 15. the death of drusus elevated sejanus. tiberius had statues of sejanus erected throughout the city, and sejanus became more and more visible as tiberius began to withdraw from rome altogether. finally, with tiberius's withdrawal to capri in ad 26, sejanus was left in charge of the entire state mechanism and the city of rome.