Detention in flagrance and pretrial detention are perceived as the “original sin” of the Mexican criminal justice system. However, empirical research on the relationship between them and their procedural consequences is scarce. That is, little is known in Latin America about whether detention in flagrance predicts pretrial detention and about the specific impact of each of them on the outcome of a criminal proceeding. Using a novel database compiled in the State of Mexico between 2010 and 2014, we examine whether: (1) detention in flagrance is associated with pretrial detention; and (2) if detention in flagrance and pretrial detention are associated with case disposition. Contrary to our expectations, we found no evidence of the association in the first point (1). With respect to the second point (2), detention in flagrance is associated with a greater probability of conviction in an abbreviated trial and a lower probability of the case being dismissed or closed. Preventive detention also predicts a greater likelihood of conviction in the oral trial. This reveals a more complex picture than the one often presented on flagrant detention and pretrial detention. In the final part, we discuss how our research modifies and confirms previous findings.