Prof Avril Henry found dead days after police broke into her house following a tip-off from Interpol about the purchase

A retired academic is believed to have taken her own life using an illegally imported “euthanasia kit” a few days after police raided her property following a tip-off from Interpol.

Prof Avril Henry, 81, a member of the pro-euthanasia group Exit International, is said to have surrendered some of the drugs in her kit after police forced their way into her home – but kept half without officers realising.

Police were called back to her cottage in the village of Brampford Speke in Devon on Wednesday after she was discovered dead.

The Australian euthanasia campaigner Prof Philip Nitschke, who founded Exit International, spoke to Henry after the police raid and said she was furious at the intervention by Devon and Cornwall police.

He accused the force of being heavy-handed and said Exit International was warning other members of what has happened. Police have confirmed they visited Henry on Friday because of concerns over her welfare but refused to comment in detail. They will prepare a file for the coroner.

Nitschke said Henry, who was a professor of English medieval culture at the University of Exeter until 2000, had a series of illnesses and conditions including chronic ear infections and tinnitus, high blood pressure that led to cardiac and renal problems, swollen feet, incontinence and urinary infections.

He said: “She described her life as becoming a complete misery. She could not lift anything and was living an impossible existence. It got to the point she did not have a life she wanted to live.”

She had friends and was a popular figure in her village but had no known close family.

Nitschke added: “She had a formidable reputation as an academic of many years standing, but her health had drastically deteriorated. She had no one terminal illness but had a myriad of problems. She was pretty much housebound.”

She approached Nitschke about the possibility of travelling to Switzerland for an assisted suicide, but became too ill to travel. She was also said to be keen to die in her own beloved home and be buried in her orchard.

An ambulance crew was called to her property when police attended. A call incident report seen by the Guardian described it as a “very difficult situation”. It continued: “This lady has ordered an online suicide medication. The police have tracked the package to her house. This medication is in the house but can’t be found.”

Facebook Twitter Pinterest Philip Nitschke Photograph: Graham Turner/The Guardian

The report also says the police visit took place after Interpol in Manchester intercepted information about chemicals coming from Mexico.

Henry gave Nitschke a copy of a note she intended to leave, which he said she was happy to be published. It is dated Saturday 16 September. It said she was about to take the drugs, adding that the decision was her own and taken with the support of her family.

She described the law on suicide in the UK as illogical and cruel.

After the police visit Henry postponed her suicide, but Nitschke said she died earlier this week. He said: “Police need to realise that in the UK suicide is not a crime, and mental health authorities need to recognise that not everyone who seeks to end their life is in need of psychiatric intervention.

“Her death was a clear case of ‘rational suicide’ and her decision to die at her own time and in her own place should have been respected. As it is the authorities did everything they could to make her last days on this earth a misery.”

Nitschke said that in light of events in Exeter, Exit International would be contacting its 1,000-plus UK members warning them what had happened.

He said he had heard of another Exit member – a woman in her 70s from a different part of the UK – who reported that police had entered her house on the basis of information from Interpol. Drugs had been confiscated and she was due in court later this month.

Exit International is a not-for-profit Australian company that says it has an online membership of 18,000 supporters around the world.

It says the average age of Exit members is 75 years. A significant minority, it adds, are seriously ill.

Nitschke burned his medical practising certificate in November after a long-running fight with the Medical Board of Australia but said he would continue to advise terminally ill patients about how to take their lives.

Devon and Cornwall police refused to say if they had taken any drugs from Henry and declined to address complaints about how their officers had acted.

A spokesman said: “Devon and Cornwall police attended an address in Brampford Speke on 15 April following concerns for the welfare of a person within the property, and therefore entrance was forced.

“No criminal issues were highlighted during this incident and the matter was left in the hands of medical and mental health professionals.

“Police were called to the same address in Brampford Speke on 20 April following reports of a body of a woman in her 80s being discovered. This death isn’t currently being treated as suspicious and a file is being prepared for the coroner.”

Neighbours described Henry as a “lovely” lady. Former dentist Geoffrey Langley, 77, said: “I have known her for quite a long time. She was a woman of strong views. She was on the parish council for many years and could be quite controversial.

“Sadly, she had not been in good physical health for a long while. but she was brave and determined to keep mobile.”

In the UK, the Samaritans can be contacted on 116 123. In the US, the National Suicide Prevention Hotline is 1-800-273-8255. In Australia, the crisis support service Lifeline is on 13 11 14.

• This article was amended on 22 April 2016 to correct Prof Avril Henry’s title. We originally called her Dr Henry.