«The Hanged Man» by Walter Satterthwait

Croft looks for evidence to free a tarot reader accused of killing a satanist.
Strong cosmic energy and stunning scenery have long made Santa Fe a destination for New Age enthusiasts. At a gathering of New Mexico's most renowned mystics, known satanist Quentin Bouvier flaunts a priceless tarot card; a few hours later, he is found hanged from a rafter, head bashed in, the card missing. Suspicion falls on Giacomo Bernardi, a tarot reader and owner of the scarf with which Bouvier was strung up. To crack the state's airtight case, Bernardi's lawyer hires Joshua Croft, a private investigator with no patience for the supernatural but a strong understanding of earthly vice.
To prove Bernardi's innocence, Croft reconstructs the events of that strange, deadly dinner party, interviewing all the participants and finding that even the spiritually minded are capable of murder.