Shortly after leaving the consulship, Clemens was executed, allegedly for atheism, although the exact circumstances remain unclear.
His grandfather, Vespasian's brother Titus Flavius Sabinus, consul in AD 47, was captured and slain by the forces of Vitellius, who burnt the capitol, but the rest of the family escaped.
Suetonius claims that Domitian was motivated by his love for his cousin's wife, Julia Flavia (who, as the daughter of his brother Titus, was also his niece).
[6] According to Cassius Dio, Clemens was put to death on a charge of atheism, for which, he adds, many others who went over to the Jewish opinions were executed.
[12] Some scholars identify Clemens with "Ketia bar Shalom", whom the Talmud described as a Roman senator who converted to Judaism and managed to save the Jews from a decree of persecution, before himself being executed.