He has been able to forge trusting relationships with his subjects, enabling him to extract the facts behind their infamous acts and identify what motivated them to commit their horrific crimes. Carlo's investigative achievements are remarkable, but what wasn't known to his readers is that, while working on The Ice Man, he learned he had amyotrophic lateral sclerosis (ALS), a terminal illness that causes all of the muscles in the body to atrophy over time. Suddenly, after years of penetrating the minds of killers, Carlo found himself being pursued by the grim reaper. But rather than lying down and succumbing to the disease, Carlo continued to work, and his books are still being published, to both critical and commercial acclaim.