At noon, a female corpse was found partially submerged on the shore of a lake. The air temperature was 26.7 ℃ and the water temperature was about 15.6℃. Rigor mortis was not evident and the body’s temperature was 15.6℃. Livor mortis showed a noticeable reddening on the victim’s back that did not disappear when pressed. Bacterial activity was not significant, and the lungs were filled with water. What is the estimated PMI?

Justify your claim using evidence from the preceding paragraph. Show all work and calculations.