After the death of Tiberius’s son Drusus, Praetorian Prefect Lucius Sejanus’s influence grew exponentially. Sejanus was the defacto ruler of Rome from 26 AD until his fall from power 5 years later.
Source: http://feedproxy.google.com/~r/TheHistoryOfRome/~3/B_DusztotN0/58-_Partner_of_my_Labors.mp3