Libor arrests 'imminent' as US authorities close in A legal expert invovled with at least one of the potential suspects said: "The problem for the UK authorities will be in proving that Libor was manipulated, the standard required for a criminal conviction, as opposed to showing attempts were made." The US and European authorities are understood to be analysing emails between a ring of traders that they suspect of colluding to manipulate Libor. The emails could form a key part of any prosecution. It is not certain at this point which banks the individuals worked for. Most of them are understood to have already moved on to different employers.