That he is connected with the crime is eminently probable, if not absolutely certain.
It is to be remembered that for a month--according to Burchard--he had been in the habit of visiting Gandia almost daily.

He comes to Vannozza's villa on the night of the murder.

Is it too much to suppose that he brought a message from some one from whom he was in the habit of bringing messages?
He was seen last on the crupper of Gandia's horse as the latter rode away towards the Jewish quarter.( 1) Gandia himself announced that he was bound on pleasure--going to amuse himself.

Even without the knowledge which we possess of his licentious habits, no doubt could arise as to the nature of the amusement upon which he was thus bound at dead of night; and there are the conclusions formed in the morning by his father, when it was found that Gandia had not returned.
1 The Ghetto was not yet in existence.

It was not built until 1556, under Paul IV.
Is it so very difficult to conceive that Gandia, in the course of the assignation to which he went, should have fallen into the hands of an irate father, husband, or brother?
Is it not really the obvious inference to draw from the few facts that we possess?
That it was the inference drawn by the Pope and clung to even some time after the crime and while rumours of a different sort were rife, is shown by the perquisition made in the house of Antonio Pico della Mirandola, who had a daughter whom it was conceived might have been the object of the young duke's nocturnal visit, and whose house was near the place where Gandia was flung into the Tiber.
We could hazard speculations that would account for the man in the mask, but it is not our business to speculate save where the indications are fairly clear.
Let us consider the significance of Gandia's tied hands and the wounds upon his body in addition to the mortal gash across his throat.