Aino Nykopp-Koski was a practical nurse and home care worker in Helsinki. In December 2010 the Helsinki District Court convicted her of murdering five elderly patients and attempting to murder five more between 2004 and 2009, and sentenced her to life imprisonment. The court found that she had secretly given them medicines, mostly sedatives, that no doctor had prescribed. Yle, the Finnish public broadcaster, described it at the time as the largest murder trial in Finnish legal history, and in 2025 it called her case the only exposed series of killings set inside the Finnish health care system.
She has denied every charge from the start: during the police investigation, at trial, on appeal and in later parole hearings. The Helsinki Court of Appeal upheld the life sentence on March 29, 2012. She has since changed her name more than once and, by 2025, was known in the courts as Ann Maria Gyllgren. The Court of Appeal refused her release on parole in 2020, 2022 and 2025, and in June 2026 she applied for the fourth time.
Yle gives her year of birth as 1950. Little has been made public about her early life, family or training. In the court coverage she appears as a perushoitaja, the Finnish term for a practical or basic nurse, who also worked in home care, visiting elderly clients in their own homes. Over the years covered by the convictions she worked in two Helsinki hospitals, in a care home and in home care.
When she went on trial she had been in custody since the spring of 2009. Yle reported in December 2010 that she had been held on remand for about 18 months and had recently married a man 20 years younger than herself. In March 2012 Yle reported that she had married in prison and changed her surname.
In April 2025 Yle published a detailed account of the case, drawing on the court record, that described warning signs years before her arrest. In 2003 and 2004 she worked as a practical nurse on a ward of a Helsinki hospital eye clinic, where she came under suspicion for thefts from patients. The hospital district's head of security learned that patients on her shifts had suffered unexplained and sudden turns for the worse after eye surgery, and that some elderly patients showed signs of poisoning that no one could explain. Money had also gone missing from some of them.
The matter was not reported to the police. Searches carried out after her arrest found property that had been stolen from patients, among them a designer umbrella, according to Yle.
The victims of the five murders were elderly and in poor health, and the courts found that their age and illness had left them unable to defend themselves. Finnish courts and the press have not published their names. Yle's 2025 account sets out who they were by year, age and place.
The first, in 2004, was a woman of 80 in a private hospital in Helsinki, recovering from routine surgery. The second, in 2005, at the same hospital, was a man of 70 who had Alzheimer's disease. The third, in 2006, was a woman of 85 who was receiving home care in her own home. The fourth, in 2008, was a woman of 90, also in home care at home. The fifth, in February 2009, was a woman of 77 with a mental illness who lived in a care home run by a Helsinki seniors' foundation. That death was the last murder proved against her.
In each case the court found that she had given the patient medicines that were not part of the patient's treatment, in amounts that killed them. The courts did not find a motive, and none has been established since. When the psychiatric findings were published in November 2010, Yle reported that no apparent motive had been identified.
The five attempted murders, by Yle's 2025 account, were spread across the same years: three in 2006, one in 2007 and one in March 2009. She was also convicted of aggravated assaults, which Yle placed in 2005, 2006 and 2008. One of them, by Yle's reports in 2010 and 2012, was against a co-worker. When the appeal opened in November 2011, the state prosecutor, Leena Metsäpelto, told the court that the defendant had given patients lethal medicines and had then called the emergency services, and often the patients' relatives, apparently to keep suspicion away from herself. "She had a pattern that she followed," the prosecutor said.
During the months she worked at the care home where the fifth murder took place, more than ten elderly residents died within a couple of months, according to Yle. Only one of those deaths could be properly investigated, because the others had been cremated before anyone suspected a crime. That one death was proved to be murder. Yle has reported that not all of her killings may have come to light, but no charge was brought over the other deaths, and they remain unexplained in the court record.
The Yle crime reporter Tuomas Rimpiläinen, writing in April 2025 about killers in Finland who had taken more than one life, quoted the criminologist Martti Lehti, since deceased, who had said that Finland's otherwise effective system of death investigation had a gap where this kind of crime was concerned, and that killings in health care might go undetected.
The case came to light through a call she made herself. At 12:31 p.m. on March 14, 2009, she rang the Helsinki emergency center and said she had found an elderly woman, one of her home care clients, collapsed on the floor.
The woman recovered in hospital. Tests found sedatives that she had not taken herself, and she told doctors she suspected her carer. It took her until the fourth day to convince a doctor, and the police were then told. Yle reported in 2011 that the Helsinki criminal police began their investigation in March 2009, after the patient said the home carer had tried to poison her, and that unexplained deaths at the nurse's earlier workplaces were then examined. She was arrested that month.
Yle broadcast a recording of the emergency call in 2025, with the address and the patient's words removed.
The trial in the Helsinki District Court was the largest murder trial in Finnish legal history, Yle reported. One of the patients was exhumed during the investigation.
A psychiatric examination was carried out before the verdict, and the court published its findings in late November 2010. The psychiatrists concluded that she had a sociopathic personality disorder but understood the consequences of her actions, and the court held her criminally responsible. Yle's later accounts describe the diagnosis as antisocial personality disorder with many psychopathic traits. According to the examination, as Yle summarized it in 2025, she lacked the capacity for empathy, her condition could not be cured, she had a marked tendency to lie and an unusual ability to manipulate people through friendly behavior, she had low self-esteem, and she showed no remorse.
The court gave its verdict in December 2010, and Yle reported it on December 22. She was convicted of five murders and five attempted murders and sentenced to life imprisonment. In later summaries Yle reported that the court had found the killings premeditated and the victims wholly defenseless because of their age and poor health, and that the life sentence also covered three aggravated assaults, an aggravated theft, two thefts and two narcotics offenses. She denied all the charges and said she would appeal.
The Helsinki Court of Appeal began rehearing the case on November 7, 2011. Police brought her from prison to the hearing. Yle called it an unusual trial for Finland and the largest murder case in the country's modern history. The court planned to hear about 90 witnesses, and the hearing was expected to last until the end of December.
She asked the court to overturn the life sentence and release her. Her lawyer, Heikki Lampela, said she remained certain of her innocence. "My client believes that the verdict will change. My truth is my client's truth," he told Yle. He declined to give his own view on whether a new trial had been needed. The prosecutor, Metsäpelto, asked for the life sentence to stand and told the court that the defendant had shown no remorse. "Nykopp-Koski gave her patients medication with the intent of killing," Yle quoted her as saying.
On March 29, 2012, the Court of Appeal upheld the District Court's life sentence for five murders and five attempted murders. She continued to deny the charges, and Yle reported that she would seek leave to appeal to the Supreme Court. The conviction stands, and later court decisions on her release have treated the life sentence as final.
A prisoner serving life in Finland may apply to the Helsinki Court of Appeal for release on parole, and the law sets a minimum of 12 years in prison before release is possible. Yle reported in 2025 that the average time served on a life sentence was about 14 years and 10 months; Kaleva gave the figure in 2020 as 14 and a half years. Under current case law, Kaleva reported, the method and number of killings often lengthen the time served, while real remorse, good conduct, good prospects of returning to society and old age can shorten it.
She first applied in 2019, under the name Ann-Maria Myllgren, asking to be released from March 18, 2021, the date on which, Kaleva reported, she would have served 12 years. Her conduct in prison had been good, but the Criminal Sanctions Agency (Rikosseuraamuslaitos) did not support her release. The Court of Appeal heard the application behind closed doors, with her taking part by video link from prison, and rejected it on May 15, 2020. It held that the number of victims and the nature of the crimes meant she had to serve clearly longer than the 12-year minimum, and it also cited the risk that she would commit another violent crime. A confidential statement from the Psychiatric Prison Hospital on that risk carried weight in the decision, Yle reported.
She was moved to an open prison in 2020, and over the following years she was granted leave without an escort. Yle reported that the leaves had passed without problems and that she had committed no new offense in prison. In 2022 the Court of Appeal rejected a second application, made by then under the name Ann Maria Gyllgren.
Her third application was heard on April 17, 2025, the Thursday before Easter. She was 74. She took part by remote link and sat with her back to the camera while the media were allowed to film the opening of the hearing, and the rest of the hearing was held in private. She asked to be released as soon as possible. Counting her time on remand, she had then been in custody for just over 16 years.
Yle set out the considerations on each side: her good record in an open prison and on unescorted leave favored release, while the nature of the crimes, several planned killings of defenseless people, weighed against it. She still denied that she was guilty of the murders.
On May 13, 2025, the Court of Appeal rejected the application. It found that she had not yet served long enough for her crimes, that she had to serve clearly more than the 12-year minimum, and that the nature and number of her offenses justified a longer term than the average. It also cited assessments of the risk that she would commit another violent crime; the Psychiatric Prison Hospital's statement on that risk was again confidential. The Criminal Sanctions Agency did not support her release. Yle noted that because she had changed her name several times, court records show her under different names.
In June 2026 she filed a fourth application for parole with the Helsinki Court of Appeal through her lawyer, Yle reported on June 24, 2026. She was 75 and had served 17 years. She asked to be released as soon as possible, on the ground that she had already spent a long time in prison, and asked for an oral hearing. No hearing date had been set when Yle reported the application. She had never admitted the killings.
Yle has called her the worst serial killer in Finland's recent history and, in a 2025 survey of Finnish killers with more than one victim, listed her among those convicted of three or more killings, with her case the only one exposed inside the health care system. The Finnish press has often called her "myrkkyhoitaja", the poison nurse. She has given no public account of the killings and has maintained her innocence throughout.
Several points remain unresolved. The courts did not establish a motive. The deaths of more than ten residents at the care home where she worked in 2009 could not be examined because the bodies had been cremated, and only one of them was proved to be murder; Yle has written that not all of her killings may have been found. The near-misses on the hospital eye clinic ward in 2003 and 2004 were not reported to the police at the time, and it has not been reported whether any of those events led to charges. None of these matters has been the subject of a further prosecution.
1950: Born, according to Yle.
2003 to 2004: Works on a ward of a Helsinki hospital eye clinic; suspected of thefts from patients; unexplained deteriorations among patients on her shifts are not reported to the police.
2004: First murder, a woman of 80 in a Helsinki private hospital.
2005: Second murder, a man of 70 at the same hospital.
2006: Third murder, a woman of 85 in home care; three attempted murders.
2007: One attempted murder.
2008: Fourth murder, a woman of 90 in home care.
February 2009: Fifth murder, a woman of 77 in a Helsinki care home.
March 14, 2009: She calls the emergency center to report a home care client collapsed; the client survives and tells doctors she suspects her carer.
March 2009: Arrested; Helsinki criminal police begin the investigation.
November 2010: The District Court publishes the psychiatric findings; she is held criminally responsible.
December 2010: Helsinki District Court convicts her of five murders and five attempted murders and sentences her to life imprisonment (reported by Yle on December 22).
November 7, 2011: Rehearing opens at the Helsinki Court of Appeal.
March 29, 2012: Court of Appeal upholds the life sentence.
2019: First parole application, as Ann-Maria Myllgren.
May 15, 2020: Court of Appeal rejects the application.
2020: Moved to an open prison.
2022: Second application, as Ann Maria Gyllgren, rejected.
April 17, 2025: Closed hearing of the third application.
May 13, 2025: Third application rejected.
June 2026: Fourth application filed; no hearing date set by June 24, 2026.