http://en.wikipedia.org/wiki/Marcus_Arrecinus_Clemens_(prefect_38)

Marcus Arrecinus Clemens

Marcus Arrecinus Clemens (fl 1st century) was a prefect of the Roman imperial bodyguard, known as the Praetorian Guard.

Born in Pisaurum, Italy, Clemens came from obscure origins and according to the historian Suetonius, his family were of Equestrian rank. He was the son of Arrecinus and wife Tertulla.

His wife could have been named Julia, and his sister was Arrecina Clementina, also born in Pisaurum, Italy, c. 12, who became the wife of Titus Flavius Sabinus. His children were Marcus Arrecinus Clemens and Arrecina Tertulla, who became the first wife of the future Emperor Titus [Suetonius, Titus 4.2.] There is a possibility that Clemens was related to the paternal side of Vespasian. Vespasian's paternal grandmother bore the cognomen Tertulla and this cognomen was also borne by both his daughter and his mother.

Clemens served as prefect in the reign of Emperor Caligula, from 38 until 41, which he had honourably commanded. On 27 January 41, however, he became one of his Emperor's murderers, also taking part in the murder of the Empress Caesonia and their daughter, as well as in the proclamation of the next Emperor Claudius.

Source :

https://en.wikipedia.org/wiki/Marcus_Arrecinus_Clemens_(prefect_38)