Complex sentence: There have been a number of rumours why the murder of Papalia was ordered, one of them was that Papalia was getting old and was suffering from memory loss and therefore not fit to rule the Southern Ontario underworld.
Split into simpler sentences: There have been a number of rumours why the murder of Papalia was ordered. One of them was that Papalia was getting old and was suffering from memory loss and therefore not fit to rule the Southern Ontario underworld.