Blue paperback mystery with yellow dolphin bookmark

I lost my blue paperback mystery novel yesterday around 3pm near the Del Rio Public Library on Main Street. It’s a worn edition with a creased spine and a yellow dolphin bookmark that has a tiny charm. There’s a faint coffee stain on the bottom edge and a doodle on the first page. This book is sentimental to me—it was a gift from my sister before our trip to Eagle Pass. If anyone found it, I’d really appreciate getting it back. I’m in the Del Rio / Eagle Pass area and would happily come pick it up nearby.