YA Fiction - 2 sisters live with mom and abusive stepdad, run around town solving mysteries. “Creepy” cop follows them but is actually protecting them and is bio dad. Cover: brown? Read in 2010’s.

[Betsy]

YA Fiction-2 sisters live with mom and abusive stepdad, run around town solving mysteries, “creepy” cop follows them but is actually protecting them and is bio dad, possible brown cover? Read in 2010’s

[Kris]

Betsy, is this a mystery book for teens?

Can you describe some of the mysteries the sisters try to solve?
Story's time period?

How far into the book do you learn the cop is their biological father?