At what time did this man die and who killed him?

Dunking is the morning baker at the newton bake shoppe. He usually arrives at the shop at 3:00 am to begin the days baking. when he arrived last tues however he was met with a horrible suprise. As he opened the walk in refrigerator to pull out the ingredients he discovered a body. According to the statement he immediately called the police who arrived with the coroner at 3:30 am. The police report noted the following facts: The body was identified as that of the bake shops owner Mr Chris P Kreem. When the coroner arrived he immediately measured the temp of the body as 57 degree F. At 4:30 he measured the temp again at 52.5 degree F. The temp of the walk in refrigerator is a constant 37 degree F. The body showed a severe head injury but no signs of being moved. The night baker Krueller closed up the previous evening at 7:00pm. Witnessed verified he arrived at home at 8:00 and remained home all evening. The cleaning staff cleaned the bakery between 1 and 2 am. They do not enter the refrig or freezer which are left locked by the night baker. Neither the day or night baker nor the cleaning staff noted anything unusual. The owners wife,Boston Kreem, said that on the previous evening she and her husband enjoyed a movie and a midnight snack before retiring to separate bedrooms. Mrs Kreem claims that Mr.Kreem had planned to leave home at 2:30am to open up shop with the day baker. The day baker Dunkins wife claims that he was home since 5 pm the previousday until he left for work at 2:30 am on tuesday. Who killed Chris P Kreem?