Aino Nykopp-Koski was born in November 1950 in Finland. Details about her early life and background are limited. She pursued a career in nursing, a profession that provided her with access to vulnerable patients. Her employment history included positions at various hospitals, care homes, and private residences between 2004 and 2009.

Between 2004 and 2009, Nykopp-Koski exploited her role as a nurse to administer lethal doses of sedatives and opiates to elderly patients, aged between 70 and 91. She was convicted of murdering five patients and attempting to murder five others. Despite the severity of her crimes, no clear motive was established. Her actions were characterized by a pattern of administering fatal medications, followed by contacting emergency services and the victims' families to deflect suspicion. ​

Nykopp-Koski was apprehended in March 2009. During her trial in December 2010, she pleaded not guilty; however, the Helsinki District Court found her guilty and sentenced her to life imprisonment. A psychiatric evaluation diagnosed her with antisocial personality disorder and psychopathy, but she was deemed legally sane and responsible for her actions. Her conviction was upheld by the Helsinki Court of Appeals in March 2012, and the Supreme Court of Finland dismissed her appeal in November 2012.