According to The Associated Press, Montalván served in the army for seventeen years. After his military career ended, he partnered with a service dog named Tuesday to help him with his post-traumatic stress disorder. Montalván went on to collaborate with various co-writers to write books on how Tuesday affected him: Until Tuesday: A Wounded Warrior and the Golden Retriever Who Saved Him (2011), Tuesday Tucks Me In: The Loyal Bond Between a Soldier and His Service Dog (2014), and Tuesday Takes Me There: The Healing Journey of a Veteran and his Service Dog (2016).
Here’s more from USA Today: “His friend and co-author Ellis Henican called Montalvan’s death a ‘huge tragedy.’ ‘He made great progress,’ said Henican, who had been working with Montalvan on his followup to his bestseller for the past year. ‘This PTSD thing is real.’ Henican and Montalvan’s book, Tuesday’s Promise, is finished and is scheduled to be published in May by Hachette Book Group, Henican said.” (via The Houston Chronicle)