Request #199

I read this book in 1975 or 1976 although it could have been written earlier. It was purchased from Scholastic or Weekly Reader. The plot revolved around an unsolved murder mystery in a rural town. At the end of the story a gun is found tucked away in the rafters of an old barn. The barn might catch on fire too. I think the book’s cover may have been orange and black. I’m sorry I can’t recall much else. I’ve been searching for this one for a long time! Any suggestions would be much appreciated.