That’s not strictly true.  Since I’m getting tired of saying the same or similar things in the various threads, I’ll quote myself from another thread:
I’m certainly aware that manslaughter was a  lesser included offense that was automatically charged.  My point (maybe  poorly worded) was that it wasn’t THE primary charge, and as a result  it wasn’t argued, nor was evidence for it presented.
Why?  Because, IMO, the prosecution got swept up somewhat in the furor  and charged based on what they and everybody else “just knew” in their  gut instead of what they could prove.  Once they decided to shoot for  FDM, presenting evidence for manslaughter would have detracted from  that.  For one small (incomplete) example, if they had brought on a  medical expert to testify about the likelihood of resuscitation of a  drowned child if only the paramedics were called, they would have greatly  improved their chances of getting a conviction for manslaughter.  But  by doing that, and acknowledging any possibility that the defense’s  assertion of a drowning was true, they would have greatly weakened their  charge of FDM.
They overshot - pure and simple - and that’s a direct result of how they  decided to charge.  Blaming the jury for not convicting on manslaughter  is disingenuous. (I know we agree on that part.)
 
 
…And that’s just one tiny example from a complete layman about how they could have successfully prosecuted manslaughter, if they just hadn’t overcharged the case.