 Taking once more advantage of the ideas of the paper by Ghirardi (2000), various of the just quoted authors (Bedingham, Duerr, Ghirardi, et al. 2014), have been able to prove that it is possible to work out a relativistic generalization of Collapse models when their primitive ontology is taken to be the one given by the mass density interpretation for the nonrelativistic case we will present in what follows.