10 Cops Who Turned Out to Be Serial Killers

10 Cops Who Turned Out to Be Serial Killers

Welcome to WatchMojo, and today we’re examining the most notorious serial killers around the world who worked in law enforcement in one capacity or another before or during their horrific crimes.

Anthony Sully

In 1966, Anthony Sully joined the police in Millbrae, California, a position he held until 1974 when he quit and eventually created an electrical and construction contractor company that was based in a warehouse in Burlingame. Soon, he fell into the escort scene, befriending those in power, such as Tina Livingston. Between 1982 and 1983, with the aid of Livingston and other accomplices, Sully took the lives of six people at his warehouse. In 1983, cops matched his fingerprints to those found on barrels that contained three of his victims. By 1986, with the help of Livingston making a plea deal and testifying against Sully, the former officer was sentenced to execution. However, he succumbed to natural causes in September 2023.

Florisvaldo de Oliveira

On top of being an officer of the Military Police of São Paulo State in Brazil, Florisvaldo de Oliveira, also known as Cabo Bruno, took the law into his own hands. He was a violent vigilante who took the lives of many people around São Paulo in the 1980s. Sometimes, their appearance would be enough for Oliveira to strike. It’s also believed he led a gang that included other officers. While Oliveira was arrested in ‘83, he escaped three times. But eventually, he was sentenced to 113 years for slaying 50 people. However, in 2012, after becoming an evangelical pastor and getting support from officials, Oliveira was released after serving 27 years. Yet shortly after, he was fatally shot by a small group.

Norbert Poehlke

Between 1984 and 1985, three victims were found in the German state of Baden-Württemberg. In each case, they were shot, and then their car was used at a bank robbery where the masked assailant used a sledgehammer to shatter the security glass. This mystery person was nicknamed “The Hammer-Killer.” During the investigation, the police found evidence linking the crimes to veteran officer Norbert Poehlke, whose family was reportedly in debt. When Poehlke discovered the police were closing in, he went on sick leave. By the time the officers went to his house in 1985, Poehlke had taken the lives of his wife and son. He was later found in a car in Italy, having taken his other son’s life as well as his own.

Dennis Nilsen

In 1983, a plumber was checking out the pipes at a property in London, England, when they discovered them coated with a strange substance. After an investigation, that material was found to be human remains. This led police to the flat belonging to Dennis Nilsen, a British Army veteran who worked as a police officer briefly in 1974. The cops soon discovered further remains within the Scotsman’s residence, and he was arrested, giving a confession before retracting it later. The civil servant was found guilty of taking the lives of six people and was sentenced to life imprisonment with a minimum of 25 years. However, it’s believed Nilsen killed up to 16 people. Nilsen passed away in 2018 after complications from surgery.

Mikhail Popkov

Nicknamed “The Werewolf,” Mikhail Popkov is believed to be one of the most prolific serial killers around. Using his hometown of Angarsk, Russia, and the surrounding area, Popkov worked as a police officer and a security guard while he hunted women. He occasionally used his job to return to the scene of the crime. In 2012, DNA evidence led the police to Popkov, and he was arrested. In 2015, he was sentenced to life imprisonment for taking 22 lives. However, in 2018, he was found guilty of further cases, bringing his victim count to 78. Popkov has claimed he has killed 84 people, yet due to a lack of evidence, these couldn’t be included in his convictions.

Rosemary Ndlovu

Working as a police officer in Thembisa, South Africa, Nomia Rosemary Ndlovu was struggling with gambling addiction. As such, she used to skip work to avoid paying her debts. But in 2012, Ndlovu had a dark realization about funding her lifestyle. She would take out life insurance on family members, have them slain by a hitman, and then receive the payout. Until 2018, she did this to six people, including her sister, her boyfriend, nephews, her niece, and a cousin. However, when Ndlovu asked a hitman to take out her sister and her children, she didn’t realize the person was actually an undercover cop. In 2021, Ndlovu was sentenced to six life terms for her spree.

John Christie

In 1953, former special constable John Christie had to move out of his flat in London, England. It was then discovered that three bodies were hidden in the kitchen. For a week, Christie evaded capture before eventually being caught. While he was solely charged with the slaying of his wife, Ethel, the remains of five people in total were found on Christie’s property and buried in the garden. He also confessed to the killing of Beryl Evans. With testimony by Christie, Timothy Evans was wrongly executed for killing his wife and their daughter in 1950. It’s speculated that Christie had killed upwards of eight people. He was found guilty of Ethel’s murder and was sentenced to execution, which took place in 1953.

Gennady Mikhasevich

From the outside, Gennady Mikhasevich seemed like a decent person in the town of Polotsk in modern-day Belarus. After all, he had a family, was a part of the Voluntary People's Druzhina, was a teetotaller, and was active in local politics. However, from 1971 to his capture in 1985, Mikhasevich took the lives of many people, then robbed them and handed the items to his unsuspecting wife. Due to his voluntary police position, Mikhasevich even investigated his own crimes. There are even reports of other people being executed for Mikhasevich’s slayings. He was caught when his handwriting matched notes left on the victims. After confessing, Mikhasevich was executed in 1987. It’s speculated he took the lives of more than 55 people.

Joseph James DeAngelo

Due to advances in DNA technology, it was discovered that the mysterious assaulter and the "Original Night Stalker," who had terrorized California, were the same person. This led to the nickname “The Golden State Killer.” In 2018, using genetic genealogy with DNA evidence from the crime scenes, the police found the culprit, Joseph James DeAngelo. From 1974 to 1986, DeAngelo committed a litany of horrible crimes, even when he worked as a police officer in the state. In 2020, as part of a plea deal and the statute of limitations on assault cases, he pleaded guilty to 13 murders and 13 kidnappings and received multiple life imprisonments. However, it’s believed DeAngelo is responsible for at least 13 murders, 51 assaults, and 120 robberies.

Gerard John Schaefer Jr.

In 1972, Gerard John Schaefer Jr. had hidden his dismissal at the Wilton Manors police department for harassing women to become a Sheriff's Deputy in Martin County, Florida. Shortly after, he abducted two teenage girls. However, they escaped, and Schaefer was arrested. When he was out on bail, Schaefer officially began his crime spree by taking the lives of two teenage girls. After spending six months in jail for the kidnapping, in 1973, Schaefer was arrested for the slayings after he was seen with the victims. He was found guilty and received two life sentences. Schaefer was killed in prison in 1995. Over the years, it’s believed Schaefer could be responsible for over 28 murders, starting in 1966, earning him the nickname “The Killer Cop.”

Which of these stories did you find the most shocking? Let us know in the comments.