Glennon Engleman seemed like your average neighborhood dentist, but he was harboring a dark secret. He had a deep desire for money and power, and would do anything to get his way. Even kill.

He got a taste for killing while he was a soldier. But when the conflict between Iran and neighboring Iraq ended, his desire to kill remained.

In the early 1900s, a man lured his victims with lonely hearts ads, drained their blood, and stored their bodies in barrels filled with methanol.

Like many serial killers who get caught, Michael Bruce Ross became more reckless — attacking teenagers and young women in high-traffic areas, and often returning to where he dumped their bodies.

After experiencing severe emotional abuse as a child in the ‘60s, Michael Bruce Ross got a fresh start at Cornell University. But in his senior year, as his relationship with his fiancée began to unravel, he started acting out his perverse childhood fantasies — thrilled by the terror he could instill in his victims.

In the early 1980s, Larry Eyler haunted the highways of the Midwest, leaving the gay communities of Indianapolis and Chicago paralyzed with fear.

In the 1970s, Larry Eyler seemed like your regular, easy-going guy. Behind closed doors, he was anything but. He had an insatiable appetite to dominate. When BDSM wouldn’t do it, he hit the Midwest highways, offering desperate hitchhikers a ride and leaving behind a trail of dead bodies.

After serving his first prison sentence, Graham Young entered the world again, ready to start poisoning people once more.

Graham Young always had an obsessive personality, but when his father bought him a chemistry kit, it unlocked a terrifying interest in poisons. Before long, the teenager was poisoning mice just to see what happened. Then he set his sights on his best friend, and every member of his own family.

In 1981, Wayne Williams was a 23-year-old with aspirations of putting together the next Jackson 5. But after he’s found leaving the scene of a crime, he’s charged and convicted for two murders — and implicated in a dozen more.

In the late 1970s, a killer stalked the streets of Atlanta, Georgia, abducting and murdering young Black kids. The city was paralyzed with fear and theories abounded on the identity and motivation of the killer.

Todd Kohlhepp’s behavior was growing increasingly erratic. In the real world, he made unsettling comments to his employees and friends. Online, he continued posting a string of disturbing Amazon reviews. And on his private compound, he locked his victims inside a shipping container.

At 15, Todd Kohlhepp raped his 14-year-old neighbor, and 17 years later, he committed mass murder in broad daylight. Yet somehow, he became a pillar of society, building a successful real estate business from the ground up.

Benjamin Pedro Gonzales lived in a fantasy world. He’d imagine entire relationships that didn’t exist. And when his so-called “girlfriend” told him to get lost, he went into a murderous rage, leaving a horrific trail of dead bodies in his wake.

Joe Metheny tended to exaggerate and lie about his own life, but if half the atrocities he confessed to are true, he certainly earned his gruesome moniker.

When Harvey Carignan’s murder conviction was overturned by the U.S. Supreme Court, he no longer faced the death penalty. But he wasted no time returning to his murderous ways.

After developing a reputation in the armed forces as a hulking, scowling figure with abnormally strong hands, Harvey Carignan was stationed in Anchorage, Alaska, where his first hyper-violent murder in 1948 stunned locals.

After 14 years behind bars, Arthur Shawcross struggled to settle into civilian life. He moved from town to town, but a change of scenery didn't change the truth: Arthur was still the same killer.

Arthur Shawcross was always a little "off." As a boy, he was unsympathetic and violent, exploding with anger at the slightest provocation.

Derrick's fixation with stalking, raping, and murdering women leads him to the University of Louisiana campus, where he terrorizes students and locals alike.

Ever since he was a little boy in the ‘70s, Derrick Todd Lee liked to peep. He would stare through the window of his neighbor's house, watching women undress. But the older he got, the more Derrick realized that peeping wasn't enough for him. He wanted to hold complete power over these women. And soon, that urge turned deadly.

Love makes us say and do the strangest things. For Turner, it made him jealous, paranoid, and extremely violent.

When Chester D. Turner moved to the City of Angels, it wasn’t by choice. In fact, Turner pretty much had no say in anything during his adolescence.

In this chilling conclusion to our Working Late series, we're diving into the frightening world of medical professionals who killed again and again.

In our continuing exploration of the most popular jobs for serial killers, we're taking a deep dive into those murderers who spent time in the military. It's a job that literally taught these men to kill, and they wielded that skill with alarming ferocity.