How French justice secures convictions--Services of spies and informers utilised--The “coqueurs” or “moutons” largely found in French prisons--Baseness of the average “mouton”--One youth plans the murder of his own father--Another offers to murder his cell-companion to save him from the scaffold--The skeleton of Madame Houet brought to light after thirteen years--Clever detection in the case of Lacenaire--A whole series of murders exposed, committed by this bloodthirsty assassin--Some remarkable cases--Detection often follows--The difficulty of disposing of the remains--L’Huissier, Prevost, the “woman of Clichy” and Voirbo. French justice has always been open to the reproach of using unworthy means to arrive at its end, commendable enough in itself--the conviction of the criminal. The services of spies and informers have always been utilised in a clandestine fashion. The rule has long obtained, and indeed is still in force, of employing an agent to insinuate himself into the confidence of accused persons to worm out secrets and betray them to the authorities. The most favorable opportunity is offered by the intimacy of cell association, and it is seldom that the spy fails to come upon the secret, however carefully concealed. The system is still in force, and has been tried in notable recent cases, such as that of the truculent and mysterious Campi, the murderer. The _coqueurs_, the unofficial attachés of the police, are as old as the hills, and are to be found in every country; but their ignoble business is perhaps more widely followed in France than elsewhere. They are of two classes, those at large and those in confinement,--the latter being very generally found in French prisons. The first class live with and on the criminal class, in whose operations they ostensibly take part, so as to gather the knowledge that makes them useful to the police; but they are actively engaged in them when they find it safe and profitable. More often they prefer to inform and take the reward, but when times are bad they have been known to invent imaginary schemes and persuade their friends to undertake them, betraying the dupes when they were compromised and fully committed.