I've got my game of Cluedo from Christmas, still unopened, which will help. Anyway, I reckon the Reverend Green was done away with in the study by Miss Scarlet, using a giant dildo*, and watching on was Colonel Mustard who was doing something very unseemly with Professor Plum.
There. Case closed! Scotland Yard here I come.
* This of course relates to the 21st century. Have you seen the cost of lead piping these days?