Can anyone help me with the name of this book?

[Judy]

I read a book several years ago. A devoted mother had to institutionalize her mentally disturbed teen son. She made friends with another mother at the facility and this friend’s son was soon murdered. All signs point to the first teen being the killer but devoted mother fights to prove him innocent. Does anyone know the title of this book? It reminds me a bit of Defending Jacob. Thanks.