Cactus Heart: A David Mapstone Mystery (David Mapstone Mystery Series Book 5)

It's the sweet season in Phoenix, 1999. Christmas and the new millennium are only weeks away. But history professor David Mapstone, just hired by the Sheriff’s Office, still finds trouble, chasing a robber into an abandoned warehouse and discovering a gruesome crime that is six decades old.
Mapstone begins an investigation into a Depression-era kidnapping that transfixed Arizona and the nation: the disappearance of a cattle baron’s grandsons, their bodies never found. And although the kidnapper was caught and executed, Mapstone uncovers evidence that justice was far from done.
But this is no history lesson. The cattle baron’s heirs now run a Fortune 500 company and wield far more clout than a former-professor-turned-deputy. Then one of the heirs turns up dead....