By ending I mean the instant that Phoenix tells Lamiroir shes Thalassa.

First of all, there is the investigation when the murder took place, we're in October of the year 2025. But that crime was plannified by Kristoph Gavin, 7 years ago. However, Drew Misham was saved by his own daughter (she didn't know she had saved him.), and he only found Death seven years after.
There is the trial, when at the end Vera got poisoned (by herself).
The second Investigation begins, and you can navigate between past and present, between 2018 and 2025.
Second trial, you are again in 2025 with Apollo, Trucy, Klavier, the Judge and Kristoph.
You play and all, Kristoph is kind of guilty, and Vera awakes. You're still in 2025.
And at the end, there is Nick and Lamiroir who are talking, and you are still in october 2025.
Then, well... this is the end.
The first investagation lasted one day, the first trial and the second investigation lasted one day, and the last trial and the little end lasted one day too.
So the case lasted around 3 days.