IV drip

Nurse Who Killed 3 Patients by Mixing Detergent in Their IV Drips Blames Exhaustion

In 2016, Ayumi Kubogi, 34, a former nurse in Japan, killed three elderly patients by adding detergent to their IV drips. Earlier this month, she admitted to the murders in her trial in the city of Yokohama. She stated that although treating sick patients was “rewarding,” she was “mentally and physically exhausted” and considered quitting. 

She faces a minimum of 5 years to life in prison or the death penalty for murder. The hospital she had worked in closed after the crimes were discovered in September 2016.


Nurse Poisons Patients With Disinfectant

When the killings first took place, it showed attention to the growing shortages of nurses, which has only worsened during the Covid-19 pandemic. This places more stress on the already overworked staff, many of whom experience burnout, as was seen during the pandemic when they were on the front lines.


During her trial, Kubogi said she started developing anxiety three years after receiving her nursing certificate in 2008. At that time, she felt responsible for the death of a patient who was under her care in another hospital. Her doctor prescribed sleeping pills to help with the increasing anxiety that continued through her career. [1]


Another cause of stress Kubogi claimed was being treated badly by the bereaved families of her patients. She joined the Yokohama hospital in 2015, where most of her patients were terminally ill and elderly. 


One of Kubogi’s victims, aged 88, died after she administered IV drips mixed with detergent. The other two, aged 78 and 88, died when another nurse unknowingly administered IV drips that Kubogi had also tampered with. After her arrest, she admitted that she injected the disinfectant so that they’d die when she was off duty. That way, she wouldn’t have to discuss their deaths with their family members. [2]


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Felt more relieved than anything

Furthermore, Kubogi told the court she had planned to kill four other patients that month. She had already mixed detergent in their IV drips, but another nurse saw bubbles in the IV and a hole in the drip’s stopper. That nurse called the police, who found traces of the antiseptic on Kubogi’s uniform. She later confessed in June 2018.


“We had had no awareness that she was a problem employee,” said another worker at the hospital. Another colleague, from the previous hospital Kubogi worked at, said Kubogi “was the kind of person who was hard to figure out what she was really thinking, but she was considered competent”. [3]

Prosecutors state that between July and September 20, 2018, a total of 48 patients died at the hospital. In fact, five died in one day in August, and four on one day in September. However, Kubogi only admits to having killed three. 


Chillingly, Kubogi states she feels no regrets about her crimes “but felt more relieved than anything at that time.” The court-ordered psychological evaluations found Kubogi depressed and mildly autistic. However, the doctors said her symptoms were not directly part of her motive to commit the killings, deeming her fit to stand trial.


Kubogi is expected to receive her verdict on November 9. 

Another Case of Murdered Patients

Unfortunately, this is far from the first instance of a nurse poisoning their patients. There was also the case of Megan Haines who murdered two elderly patients through insulin injections in 2014. She was given a maximum sentence of 36 years, eligible for parole in 2041.

Her conduct was deliberate and calculating. It was a gross breach of trust and flagrant abuse of her power,” said Justice Peter Garling. “She clearly abused that position of trust. I consider this to be a significant aggravating factor. I consider the offenses to have been deliberate and calculated.”

The daughter of one of the victims, Jan Parkinson, hopes this sentence will bring change to the hospitals. “They [the Government] have to start putting cameras in and people to take care of the elderly people who don’t have families to take care of them,” she said. “There are people in those nursing homes that never get visits. Nobody knows what they’re going through. Please, I beg you, check your elderly people. If they say something to you, listen to them.[4]

Keep Reading: Doctor who scammed millions of cancer patients is jailed for 45 years


  1. “Nurse Who Killed 3 Patients by Mixing Detergent in Their IV Drips Blames Exhaustion.Vice. Hanako Montgomery. October 12, 2021
  2. “Ex-nurse goes on trial for killing 3 elderly patients at Yokohama hospital.” Japan Today. October 2, 2021
  3. “Japanese nurse ‘poisoned patients’ so they would die when she was not on shift.” Independent. Adam Withnall. July 11, 2018
  4. “Megan Haines: Ex-nurse sentenced to 36 years in jail for murder of elderly women by insulin overdose.” ABC News. Lucy Carter. December 16, 2016
Sarah Biren
Freelance Writer
Sarah is a baker, cook, author, and blogger living in Toronto. She believes that food is the best method of healing and a classic way of bringing people together. In her spare time, Sarah does yoga, reads cookbooks, writes stories, and finds ways to make any type of food in her blender.