Police have seized interview notes and emails as part of a murder investigation involving the pro-euthanasia GP Dr Alida Lancee.

The West Australian newspaper said it had co-operated with major crime squad detectives and handed over all interview notes, emails, and audio and visual recordings related to Dr Lancee.

The newspaper conducted a series of interviews with the Perth GP last month, during which she told her story of giving a lethal injection five years ago to an 80-year-old woman who was dying of emphysema and had expressed a wish to die.

The GP has said there is an urgent need for effective end-of-life legislation for terminally ill patients, a move which she believes would gather widespread support from the public.

Dr Lancee has also given a personal account of her reasons for her actions in the online book The Damage Done, published by Go Gentle Australia; an organisation launched this year to spark a national conversation about voluntary euthanasia laws.

“My bags of tricks in my palliative care repertoire are mostly useless for severe breathlessness. I could try low dose morphine, but this would create hypoxia and confusion which would be very distressing in itself.

Could I, as a compassionate human being with skills and ability to relieve another human being’s severe distress, deny this because some bad rules were in place in our society that could land me in trouble? My answer was: NO. Sometimes one needs to stand up for what is right, despite the potential personal sacrifice,” she wrote.