Unspeakable Times

33 Serial Killers Who Used Poison 

Ranker Crime
Updated January 5, 2020 43.6k views 33 items

Poison isn't just for the pages of mysteries, thrillers, and crime novels. From chronic poisoning over a long period of time, to rapid poisoning that can cause instant death, many serial killers throughout history have used poison as their main weapon. This is a list of notable murderers who used poison as their modus operandi and weapon of choice.

There are many reasons why many serial killers in history have used poison to commit their murders. One of the top reasons includes collecting insurance money. Many serial killers believed that they could get away with murder since poisoning often doesn't leave much evidence. Most victims just get sick and die, making it difficult to prove the real cause of death. Many hospital workers also used poison to systematically kill their patients, giving them high doses of prescription drugs. Many serial killers used poison with the thought of nursing their victims back to health afterwards in order to gain favor and public attention. 

A few serial killers who used poison were found not guilty by reason of insanity and spent the rest of their lives committed to an insane asylum. Others, however, served a life sentence, multiple life sentences, or were executed, in most cases. Some of these serial killers poisoned their families, including children, and even more committed multiple murders over many years.

Read on to find out which serial killers used poison, how many murders they were responsible for, and what happened to them once they were caught.
Nannie Doss is listed (or ranked) 1 on the list 33 Serial Killers Who Used Poison
Photo: Tulsa Police Department/Wikimedia Commons/Fair Use

From 1927 to 1954, Doss murdered 11 people. Using rat poison, she killed her family members, including four husbands.

She was sentenced to life in prison but did not receive the death penalty due to her gender and died in prison of leukemia.

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Famously known as America's first serial killer, Holmes opened a hotel during the 1893 World's Fair in Chicago and lured in as many as 200 victims, including his staff, hotel guests, and his lovers. He would fill guest rooms in what became known as the "Murder Castle," with gas lines to asphyxiate his victims and was in possession of numerous bottles of various poisons. Afterwards, he would make claims on their insurance policies. Holmes was hanged in 1896.

Recently, it was discovered that H. H. Holmes was probably also responsible for some of the Jack the Ripper's murders. Confirmations of these allegations are yet to be heard.

More H. H. Holmes 

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Donald Harvey claims to have murdered over 70 people while he worked in various hospitals. Official estimates put the number anywhere from 37 to 57 deaths. He had many different methods of murder but frequently used poisons such as cyanide and arsenic, which were administered in food by injection or IV. He often insisted that he committed the murders out of empathy for terminally ill patients.

Harvey was apprehended in 1987 and is currently serving 20 consecutive life sentences. 

Michael Swango
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A former licensed physician, Swango poisoned non-patients by putting arsenic in their food and drinks. With his patients, he administered overdoses of prescribed drugs or prescribed unnecessary and dangerous drugs.

Though he only admitted to four murders, it is estimated that he was involved in up to 60 fatal instances of poisoning. Swango is serving a life prison sentence without parole.