Dead mice decompose at different rates of speed depending on a number of different factors. A key factor that dictates how quickly a dead mouse decomposes is the temperature of the place where it is located. The size of mouse also plays a role, with larger mice typically taking longer to decompose.
At the temperature levels typically found in a place where people live or work, the rate of mouse decomposition usually is between one to two weeks. If the space where a mouse died is hotter, the rate of decomposition increases. The smell associated with the dead mouse lingers until decomposition is completed fully.