Situation puzzleA well for corpses

One day, I felt fed up with my younger sister’s bleat. So, I killed her and threw her body into a well. The next day, the body disappeared.

A few years later, I quarreled with a friend over a trifle and decided to kill him too and to throw his body into the well. The next day, the body disappeared.

Later, I was drunk and accidentally impregnated a girl. I killed her and threw her into the same well. The next day, her body disappeared, as all the others did.

10 years later, my boss drove me nuts. I killed him and disposed of the body in the same well. A day later, his body disappeared.

Shortly thereafter, I needed to send my mom to a nursing home, but I didn’t have enough money for that, so I killed her and threw her into the well. The next day, the body was still there. Why?