Philippa, There is a very interesting book by Sean & Síle Murphy'of Mahon Bridge (at the foot of the Comeragh Mts in Co. Waterford which has a comprehensive account of the "doings" of "Crotty the Robber" it was published back in 1999 so may not be in print but you may be lucky enough to get your hands on a copy. There is a verse of an old song , as Gaeilge, included about the location of his grave.
The book is titled "WATERFORD - Heroes, Poets & Villains "