Complete momentum maps of all fragments including neutrals arising from dissociative double ionization of C Cl4 by electron impact have been obtained. The geometry of the dissociating dication is estimated from the momentum maps. The observation of Cl2+ in the time-of-flight mass spectrum of the fragments, combined with the momentum distribution of correlated fragments, provides evidence that the geometry of the dissociating cation is significantly altered from the tetrahedral geometry of the parent neutral. These observations suggest relocation of certain atoms within the molecular ion during dissociation. The geometry of C Cl4 2+ derived from the momentum maps is in conformity with the theoretically generated structure. © 2007 The American Physical Society.