The breaks in the arm are indicative of blows from multiple angles. The end of the arm seems to have been fed through a wood chipper or something similar before being pulled out. Bruising is extensive and rigor mortis has ended, placing time of death at greater than 24 hours before the arm went on ice. Given the colour of the early putrefaction, John guesses that the arm had been dead for two or three days before the detectives found it.