What was unusual about the dead body? Scene 5

The dead body has a brand on its forearm.

The dead man’s right arm was thrust out from his dressing gown, and exposed as high as the elbow. About halfway up the forearm was a curious brown design, a triangle inside a circle, standing out in vivid relief upon the lard-coloured skin.

“It’s not tattooed,” said the doctor, peering through his glasses. “I never saw anything like it. The man has been branded at some time as they brand cattle. What is the meaning of this?”