How long after death does rigor mortis set in? Does it depend on body size?

Temperature. A copse is flaccid immediately after death, muscle stiffening, rigor mortis, commences after about three to four hours, reaches maximum stiffness after 12 hours, and gradually dissipates until approximately 48 to 60 hours (two and a half days) after death. Warm conditions and physically strenuous activity prior to death, can speed up the process of rigor mortis.