Nighthawking Detective Sergeant Adam Tyler Series, Book 2.

When a nighthawker on the hunt for antiquities instead uncovers the body of a foreign student, Detective Adam Tyler is pulled into a serpentine mystery of dangerous secrets, precious finds, and illegal dealings. You are a trespasser. You are a thief. You are a Nighthawker. Under the dark cover of night, a figure climbs over the wall of the Botanical Garden with a bag and a metal detector. It's a dicey location in the populous city center, but...