What happened to Agrippa Postumus after Tiberius became emperor?

After Tiberius became emperor, Agrippa Postumus was put to death.1

Agrippa Postumus had been named a coheir by Augustus but was later banished due to falling into disfavour. While it is possible that the order to execute him was issued by Augustus before his own death, this remains uncertain. His murder is widely regarded as an act of violence intended to secure Tiberius's power by eliminating a potential contender for the throne.123