Murder in Baldur's Gate
After declining to assist Rilsa Rael with toll collector issues, the same night a particular toll collector gets robbed and his chest of tolls stolen. Over the next few nights more collectors get hit.
While The Guild is widely suspected no culprits are captured and no one is seriously injured or killed in the robberies.
While they are pretty sure they know who is behind these thefts, the party does not act on that information.