The assassins were supported by an "underground railroad" of Serbian civilians and military officers that provided transportation and hid them; members of the Serbian military that trained them, encouraged them, and provided weapons, maps, and other information.
Mõrtsukaid toetas Serbia tsiviilisikute ja sõjaväe ohvitseride "allmaaraudtee", mis andis transpordi ja peitis neid; ja Serbia sõjaväelased, kes neid treenisid, julgustasid ning relvad, kaardid ja muu info andsid.