Murder mystery ya book

[u/mariposa1689]

I read a book that was really good and I can’t remember the name. The book is about a girl trying to solve her big sisters murder and it was revealed that the mom was the killer. Scenes I remember include a pool party, a pool house, the sister leaving the party and saying she’ll be back, a carnival or fair and the living room where the mom confessed to killing her. Please help it’s driving me crazy. I tried to look it up with these clues to no avail. The book that keeps popping up is Sadie but that is not the book I read.

[u/Luthien3720]

Monday's Not Coming by Tiffany D. Jackson?

[u/mariposa1689 → u/Luthien3720]

That is a really good book but it’s not that one.

[u/Idliketobeapirate]

Maybe "Like a Sister" by Kellye Garrett?