US DOJ Offers Immunity to Junior FX Traders in London

Reuters reports this interesting tactic which is not available to prosecutors in civil cases.  One can infer from this that the investigation into FX benchmark rigging has not made enough progress to bring any suits, but that the prosecutors believe that misconduct has occurred.  Will these offers of immunity bring in the information on senior traders and bank practices that the DOJ is looking for? Although that is uncertain, it will certainly make for some uneasy relationships within the FX trading community.