Two of Serafino Volpi's brothers were reported to have spoken to third parties of Ugolini's savings, and one of them expressed a wish to rob him.

Why this brother was neither arrested nor apparently examined, is one of the many mysteries, by the way, you come across in perusing these Papal reports.
Serafino too had mentioned himself, to a neighbour, his suspicion of the tinker's having saved money.

On the morning of the murder, Starna was known to have come to the Volpi's cottage, to have talked with Serafino, and to have left again in his company, shortly after Ugolini's departure.
After about an hour's absence, Serafino Volpi returned home, and therefore had time enough to commit the murder.

He was shown, moreover, to have been in possession of a knife, about which he could give no satisfactory account, and which might have inflicted the wounds found on the corpse.
These appear to have been all the facts which could be established against either Volpi or Starna by positive evidence, and, at the worst, such facts could only be said to constitute a case for suspicion.
Previously, however, to the trial, Starna turned, what we should call, "King's evidence," and, in contradiction to his foregoing statements, made a confession, on which the prosecution practically rested the whole of its case.

According to this confession of Starna's, on the morning of the murder he called by accident at the Volpi's, and stopped there, till after the tinker, who was an entire stranger to him, had left the house.
Serafino Volpi then offered to accompany him to his (Starna's) house, on the pretence of borrowing some tool or other.