Police are considering whether a crime has been committed in the case of a mother who died hours after being told she was ready to leave hospital.
Sian Hollands, 25, died from a blood clot at Darent Valley Hospital in Dartford, Kent on 15 November 2015.
The NHS trust apologised to her family after a coroner said she could have lived, had she been treated properly.
Previously, Dartford and Gravesham NHS Trust said it was trying to improve the care weaknesses raised at the inquest.
Kent Police said it received a request to investigate the death on 11 April 2017 and officers were currently making inquiries.
Withdrawal symptoms suspected
The force has declined to comment on who made the request.
During the inquest, Gravesend Coroner's Court heard the condition of the former drug user was put down to withdrawal after she went to hospital complaining of breathing difficulties and chest and stomach pain.
Ms Hollands was given an electrocardiogram (ECG) and methadone and told she was being discharged.
The hearing was told her partner refused to take her home because she was still unwell.
Ms Hollands had a cardiac arrest in hospital.
Dartford and Gravesham NHS Trust has declined to comment.