You don't know if something is true yet you speculate it "worked?" You don't know for certain that LE "did not examine Dina."
Neither woman had any reason to place herself at the mansion if it wasn't true. I don't believe it is fair to accuse LE of a shoddy investigation when so many details of their investigation haven't been released. A year later, LE stands firm on their conclusion.
JMO
Even in blatant wrongful convicttions, you will find LE almost always stands by their original results so that is a moot point.
Right off the top of my head, but easily found if you'd care to look per a shoddy investigation:
* the call from Jonah to Rebecca in the middle of the night seems like an essential piece of LE's theory, yet they did not recover the message nor did they bother to inspect the phone for a month(?)
* The Sheriff and two search warrants claimed Redden said he was satisfied that Adam was telling the truth, that is not true. Redden suggested a second polygraph and made no claim of truth telling
* Nina's phone records don't appear to have been looked at (or times verified) even though the Sheriff claimed the eye witness really saw her at the house late at night and that it was not Dina, Nina says she told them on Tuesday that she was there and had called Rebecca late at night, and that she claims she sent that text at a different time than what Rebecca's records show
* Dina's DNA and so forth were not taken (that has been referenced at least twice here in the past week)
* It was claimed that Dina was at the hospital and that had been proven, yet when pressed it turns out only her phone was at the hospital
What I said was that if Nina did alibi Dina, it worked - that is because they did not thoroughly check Dina out nor her alibi (see above). Why? Evidently because they relied on her phone location and her own word on it that she was at the hospital - why is it that they can't verify that on video surveillance?