Mattias Flink was born on March 8, 1970, in Falun, Sweden. He grew up in a family where his mother was a housewife, and his father and grandfather worked as gunsmiths. This family connection to firearms was an important aspect of his early life. At the age of seven, Flink joined the Scout Movement, which is a youth organization that promotes outdoor activities and personal development.

When Mattias was nine years old, his parents divorced. The divorce was described as calm and sensible. After the separation, he stayed with his father in the family home, while his mother moved to an apartment nearby. According to psychological evaluations, his mother’s departure affected him deeply. This led to feelings of alienation towards women as he grew older.

Flink attended high school, focusing on Electric Mechanical studies. After graduating, he enlisted in the Dalarna Regiment as a conscript. He aimed to become an officer in the Swedish Army and was employed there in 1993.

However, in the spring of 1994, Flink faced serious mental health challenges. He struggled with aggression, severe jealousy, sleeping disorders, and paranoia. During this time, he experienced a total mental breakdown. Reports indicated that he had been removed from a restaurant for bothering women.

On June 11, 1994, Second Lieutenant Mattias Flink shot and killed seven people in Falun, Sweden. He had consumed a significant amount of alcohol before he left home dressed in his military uniform. Flink took his Ak 5 assault rifle and 150 rounds of ammunition. He then went to a park where he randomly shot six members of the Women's Auxiliary Services. Shortly after, he shot two additional men—a cyclist and a security officer—at a nearby crossing. Six of the victims died at the scene, while one woman later died in the hospital. One person survived the assault.

Following the shootings, Flink climbed into a nearby crane to hide. After some time, he descended and began walking along an abandoned railway. He was discovered by two policemen, at which point he fired at them. The policemen returned fire, hitting Flink in the hip. He was apprehended at 03:25 and taken to a hospital in Falun.

During his trial, the prosecution made no attempt to dispute the details of the crimes. The defense argued about Flink's mental state at the time of the shootings. Experts claimed he was in a temporary psychotic state caused by alcohol. Ultimately, Flink was sentenced to life imprisonment. This case set a precedent in Sweden, allowing courts to sentence individuals for crimes committed during alcohol-induced psychosis.

Flink was initially placed in Norrköping prison but was later transferred to Beateberg prison. He received protected identity status due to the nature of his crimes and did not give interviews during his time in prison. Flink was described as calm and well-behaved. In 2008, he applied for parole, which required a psychiatric assessment of his danger to society. The families of the victims opposed his release.

In January 2008, Flink requested to limit his life sentence to 24 years, but the court rejected it. In 2010, his request was approved, and his sentence was set to 32 years. This was later adjusted to 36 years by a court of appeal, and finally, the Supreme Court adjusted it to 30 years, making him eligible for parole in 2014. Flink was released on June 11, 2014, the 20th anniversary of his crime.