Police have confirmed that two of the three deaths at Gainsborough Care Home in Swanage last year were due to natural causes.
The third death, of a 91-year-old man, will be subject to inquest proceedings overseen by HM Coroner.
Dorset Police received a report on Wednesday 23 October last year following the deaths of two men aged 74 and 91, and an 86-year-old woman.
Due to the unusual circumstances, a full investigation was launched by Dorset Police’s Major Crime Investigation Team.Initial concerns included a possible carbon monoxide link, and a 60-year-old woman was arrested to allow for evidence gathering and legal protection.
This arrest was made at an early stage and the woman was released without charge once carbon monoxide and other environmental factors were ruled out.
Further enquiries included detailed forensic pathology work, which required several months to complete.
That analysis confirmed natural causes for the deaths of the 74-year-old man and 86-year-old woman. While the death of the 91-year-old man was found to be unnatural, police confirmed there was no third-party involvement or environmental cause.
Detective Chief Inspector Neil Third said the families were kept updated and added: “We were duty bound to fully investigate the circumstances of the deaths.”
Dorset Police has concluded its enquiries but will continue to support the Coroner during the inquest process.