Justus was an honorable and learned man before his ordination.
He was baptized by Mark the Evangelist, along with his father, his mother and others.
[1] St. Mark also appointed him as the first Dean of the Catechetical School of Alexandria.
[2] Anianus, the second patriarch, ordained him a deacon, then a priest, and appointed him to preach and teach the people.
He died on the 12th of Paoni 129 AD, in the sixteenth year of the reign of Hadrian.