If you help the Gray-Manes in the quest http://en.uesp.net/wiki/Skyrim:Missing_In_Action the Justicars will come for you at some point soon in the future. Even if you never assault Northwatch Keep, simply helping gather the evidence will brand you a wanted man with the Thalmar.

If you help the Gray-Manes in the quest Missing In Action, the Justicars will come for you at some point soon in the future. Even if you never assault Northwatch Keep, simply helping gather the evidence will brand you a wanted man with the Thalmar.