Satoshi Uematsu was born on January 20, 1990, in Sagamihara, Kanagawa Prefecture, Japan. He grew up in a family where his father worked as an elementary school art teacher. Satoshi followed in his father's footsteps, training to become an elementary school teacher himself. He successfully worked in this profession for a period of time.

As a child, Satoshi was described as friendly and outgoing. He lived with his parents during his childhood, but at some point, they moved away from their home, leaving him to live alone.

Satoshi was employed at a facility called Tsukui Yamayuri En, which served as a care home for people with disabilities. He worked there for over three years, starting in 2013. He resigned from this job in February 2016. His departure from the facility came after some changes in his personality, which his neighbors noticed. They expressed surprise when they heard that he had allegedly committed crimes, as they had seen him as a good man.

On July 26, 2016, Satoshi Uematsu broke into a care center for disabled individuals in Sagamihara, Japan. Around 2:10 a.m., he used a hammer to smash a glass window on the first floor. He tied up a staff member inside and took their keys. Uematsu then moved from room to room, attacking victims who were asleep by stabbing them in the neck.

At approximately 2:30 a.m., staff members called the police. They reported a man with a knife inside the building. However, Uematsu left the care center before the police arrived. He was seen leaving the facility on security camera footage at 2:50 a.m. Armed police arrived at the scene around 3:00 a.m. to find the aftermath of the attack. They sent twenty-nine ambulances to help the injured.

Two hours later, Uematsu turned himself in at the Tsukui Police Station. He brought a bag containing kitchen knives and other blood-stained tools. A knife was found in his car parked outside the police station. Uematsu was charged with the murders of nineteen people—ten women and nine men, aged between 18 and 70. He also injured twenty-six others, with thirteen suffering severe injuries.

Prior to the attack, Uematsu had tried to communicate his views on euthanasia for disabled individuals. He had sent a letter to a government official, which detailed his plans to kill people at the care center. After an initial investigation and a brief commitment to a psychiatric hospital, he was released when doctors concluded he was not a threat.

Following his arrest, legal proceedings began. On February 20, 2017, he was declared fit to stand trial. Uematsu faced numerous charges, including nineteen counts of murder and twenty-four counts of attempted murder. His defense claimed he was mentally incompetent at the time of the crime due to marijuana use. However, during the trial, he indicated he would admit to the crime, calling it complicated to deny the charges.

On March 16, 2020, the Yokohama District Court sentenced Uematsu to death for his actions. He did not challenge the verdict nor the sentence, finalizing his death penalty on March 30, 2020, when he withdrew his right to appeal. In April 2022, he sought a retrial, but this request was dismissed in April 2023.