Anyone know where the phrase "Caught red handed!" originated from?
Also "Caught with your fingers in the till" which sounds relatively modern?(with reference to a Till(C.1900?))

The idea of being caught with red hands originally meant caught with blood still on your hands after committing a murder. It has evolved to just meaning caught doing something wrong. If I remember correctly, the idea, but not the exact phrase, dates back to around the 15th century in Scotland.

Some also advance the theory that it dates back further. Something about having a suspected theif place his hand on a hot axe to find out if he was guilty.

Brewer's Dictionary of Phrase and Fable explains 'to be caught red-handed' as 'to be caught in the act as if with blood on the hands'.

Scotland ? Well, Shakespeare has Macbeth exclaim to one of the returning murderers 'There's blood upon thy face !' At this point when these words were spoken by David Garrick, the great C18 actor, the actor playing the murderer was so taken aback that he forgot himself and , reaching to his cheek cried out 'Oh my God, is there ?'in one of the better ad libs of Shakespearean history.

Trial by ordeal was forbidden by the Lateran Council of the Church in 1215. The ordeal by fire had local variants. One was for the accused to carry a red-hot iron for nine paces, another was to have him walk over red-hot plough shares. He was found not guilty ( and here there seems to be some disagreement) depending on whether he had no burns or had no blisters or if the hurt healed within a certain time. Of course they could all be true at the same place; some of us have known magistrates as inconsistent as that !

'Caught with his fingers in the till' The word till for a drawer for cash in a shop is late C17 even though we now usually use it for the drawer of a cash register.To me the image was always that of a sneak thief or dishonest employee getting his fingers caught in the drawer in his haste to shut it when approached. This is a felicitous misreading ; it's strange how these childhood errors persist in the mind ! Unfortunately Brewer does not refer to the saying.

Thank you ...
One thing about AP,Some of the researched answers are brilliant.
I thought along the line of Methos' answer (Blood on hands) But Fred found a "Spanish Inquisition" type answer to the question!