The Secret History by Procopius

I will now show what a liar and hypocrite he was. This Liberius, whom I recently mentioned, he removed from office and in his stead appointed John, an Egyptian, surnamed Laxarion. When Pelagius, a particular friend of Liberius's, heard of this, he asked the Emperor if the report about Laxarion's appointment were true. And he immediately denied it, assuring him he had done nothing of the sort; and gave him a letter to take to Liberius charging him to stick tight to his office and give it over to nobody, as he, Justinian, had not the slightest idea of removing him from it at this time.

Now John had an uncle in Constantinople named Eudemon, of consular rank and great wealth, who was at the time Count of the imperial estates. This Eudemon, when he heard the rumor, also went to the Emperor to inquire if the office were really going to his nephew. And Justinian, in contradiction of what he had written to Liberius, now wrote a document to John, telling him to take over the office by all means, as his intentions were unchanged. John, trusting in this instruction, ordered Liberius to retire from his office as he had been officially removed. But Liberius, with equal confidence, of course, in the letter he had had from the Emperor, refused. So John went after Liberius with an armed guard, and Liberius with his own guard defended himself. During the fight many were killed, including John himself, the new Governor.