«The Invisible Assistant» by John Gaspard

There's no question it was murder. But who killed whom? 
What begins as a typical corporate event for magician Eli Marks turns into a twisted mystery when he is called to the site of a recent murder/suicide. 
Confronted by the details of the grisly crime scene, Eli must sort through the post-mortem clues - and the bickering of the officials as well as a poorly-timed allergy attack - to determine just who murdered whom.
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PRAISE FOR THE ELI MARKS MYSTERY SERIES
"You will just LOVE these books.” – VANISH Magazine
“This is an instant classic, in a league with Raymond Chandler, Dashiell Hammett and Arthur Conan Doyle.” – John Lehman, Rosebud Book Reviews
“It’s full of magic, mystery, danger and misdirection, as a good magic trick should be. I love this cozy mystery series, a thoroughly delightful read.” – Sweet Mystery Books
“Before I had even finished the first chapter I had fallen in love with Eli. He is intelligent, sensitive, witty and, suddenly, the main suspect in a series of murders…well written, fast-paced and exciting.” – The Frugal Mennonite
“This story is very well written and fun to read. I would definitely read another Eli Marks Mystery!” – A Simple Taste for Reading
“Gaspard's latest Eli Marks mystery has as many tricks up its sleeve as its likable magician-hero. As the body count rises, so does the reading pleasure.” – Dennis Palumbo, Author of the Daniel Rinaldi Mystery Series and Co-Writer of My Favorite Year
“Readers, get ready for your mind to expand as Eli Marks returns and uses his powers of prestidigitation, intuition and deduction to solve another mystery. If David Copperfield and Sherlock Holmes had a child, it would be Eli Marks.” – Scott Wells, The Magic Word Podcast