Master of the St. Mary Polyptych (attrib.)
The Palazzo Bellomo St. Lawrence Altarpiece: Detail, Lawrence is Arrested
The Golden Legend explains how Lawrence came to be arrested after the execution of Sixtus:
And the blessed Laurence ran after him [Sixtus] and said: "Forsake me not, holy father, for I have dispended the treasures that thou deliveredst to me." And when the knights heard speak of the treasures, they took Laurence and brought him to the provost, and the provost delivered him to Decius. And Decius Cæsar said to him: Where be the treasures of the church, which we know well that thou hast hid? And he answered not. Wherefore he delivered him to Valerianus the provost to the end that he should show the treasures and do sacrifice to the idols, or to put him to death by divers torments.
Lawrence is of course the haloed figure in the dalmatic that he wears in all the panels. The man in chain mail who stands behind him and grasps his right side should be one of the "knights" who "took Laurence and brought him to the provost." Whether the man on the throne is that provost or Decius himself is hard to tell, but the small axe held by the man on the far left could be a reference to the emperor's expostulation, "Have the magisterial rods so wholly lost their stern control? Has gentle lenity so blunted the axe of authority?" (Prudentius II, 107).
View this image in full resolution.
View the whole altarpiece.
Read more about St. Lawrence.
Photographed at the Palazzo Bellomo by Claire Stracke, shared under Attribution-NonCommercial-ShareAlike license.