IMO, if Jessica's death was an accident, LE would be more than happy to make the announcement. I don't think that her death was an accident.
I think they were afraid of being accused of not investigating the case.
Anybody remember the 1st press conference where the DA (or somebody) was obviously anxious & upset and blurted out "We're a good Christian community here!" WTH was that about? There was some reason he felt compelled to state that.