Recent measurements of the transient laser-induced fragmentation of photoexcited 1,3-cyclohexadiene undergoing isomerization have seen that some of the fragments have higher velocity at the pump–probe delay corresponding to the time of passage through a conical intersection (CoIn). (http://arxiv.org/abs/1212.3728) Here we explore several possible explanations related to the electronic and ionic structure of molecules in the vicinity of CoIns and suggest some experimental tests that could illuminate the mechanism and ultimately control this behaviour.