Colley was one of the leaders of a mob which gathered at Tring in April 1751 and seized an elderly couple, John and Ruth Osborne, from the local workhouse, accusing them of witchcraft. The mob subjected the pair to a dunking at a nearby pond in Wilstone. Ruth was beaten and dragged through the water repeatedly, until Colley drowned her by turning her face-down with a stick. John survived and testified at Colley's trial.
Colley was convicted of murder and hanged in chains at Gubblecote Cross.
John Brand; Henry Ellis (1842). Observations on popular antiquities: chiefly illustrating the origin of our vulgar customs, ceremonies, and superstitions. Charles Knight and Co. p. 20.
Gijswijt-Hofstra, Marijke; Levack, Brian P.; Porter, Roy; Ankarloo, Bengt (1999). Witchcraft and magic in Europe: the eighteenth and nineteenth centuries. Continuum International Publishing Group. p. 195. ISBN978-0-485-89005-1.