To briefly recap, Paulette disappeared in March, the police came and searched the house, both parents acted really oddly (especially the mom), the police came back to recreate the scene of the night of her disappearance, found Paulette's body in "an opening between the base of the bed, the floor, and the mattress", detained and interrogated the parents and the girl's nannies, made public no conclusions, sat on the story for six weeks, and then on Friday suddenly announced that she had smothered herself. This should be in a textbook about how a government can earn the scorn and distrust of its constituents. Freak things do happen in life, and if you told me that a young, developmentally challenged girl (which Paulette was) had fallen awkwardly in her sleep and suffocated, I wouldn't necessarily think you were full of it. However, given that the government waited so long, that the police could conduct a search of the house and miss the body of the girl they were looking for in her own bedroom, that both parents could behave so oddly in interviews (the mother's emotions, which appeared utterly incongruent with the circumstances, were especially remarkable), and that Paulette Gebara's father reportedly has connections to Mexico State governor Enrique Peña Nieto's political operation, you'd have to be as credulous as a first-grader not to smell a rat. This feels like one of the cases (say, the assassination of José Francisco Ruiz Massiueu) that you read about in Mexican history books, content in the knowledge that such episodes are a thing of the past. Except, as we see, when they aren't.
Malcolm Beith wrote that "[i]f Pena Nieto runs [for president], the 4-year-old corpse of Paulette should be pictured alongside every cheery photo op he ever does". With Peña Nieto endorsing the investigation, it's hard to argue with that sentiment. Because the story broke the boundary between a strictly political and a mainstream news story, it also seems like something that could significantly eat into his popularity.