The most common triggers for homicide are fear, rage, revenge, money, lust, and, more rarely, sheer madness. This isn't an exact science, of course. Any given murder can have multiple triggers. Sex and revenge seem to be common partners in crime. Rage, money, and revenge make for a dangerous trifecta of triggers, as well.

This book offers my memories of homicide cases that I investigated or oversaw. In each case, I examine the trigger that led to death. I chose this theme for the book because even though the why of a murder case may not be critical in an investigation, it can sometimes lead us to the killer.

And even if we solve a case without knowing the trigger, the why still intrigues us, disrupting our dreams and lingering in our minds, perhaps because each of us fears the demons that lie within our own psyche-the triggers waiting to be pulled.

Lt. Joe Kenda, a twenty-three-year veteran of the Colorado Springs Police Department, spent twenty-one years chasing killers as a homicide detective and commander of the major crimes unit. Kenda and his team solved 356 of his 387 homicide cases, getting a 92 percent solve rate-one of the highest in the country. After retiring from law enforcement, he starred in Homicide Hunter: Lt. Joe Kenda, an American true-crime documentary series that ran for nine seasons on the Investigation Discovery network and was aired in sixty-nine countries and territories worldwide. At its peak, Homicide Hunter averaged 1.9 million viewers in the US. See Lt. Kenda on his new crime series, American Detective, available to stream now on discovery+.