Red paperback mystery with green bookmark

I lost my red paperback mystery novel yesterday around 3pm near the Burton Barr Central Library on Central Ave in Downtown Phoenix. It's a 320-page HarperCollins paperback with a desert sunset cover and a small crease on the top corner; inside there's a green bookmark with a tiny cactus illustration and a dog-eared page on 93 where I wrote a note for a friend. It was a gift from my grandmother and has a lot of sentimental value—I really need it back. If anyone found it, I’d be truly grateful to get it back.