John Christopher Walmsley, 35, is charged with aiding and abetting the suicide of his girlfriend, atroubled 25-year-old who had athree-year-old daughter, by encouraging and facilitating her to take a lethal cocktail of drugs between the night of January1 and the early hours of January2, 2011.

The pair had been together for about four months and the woman, said to be a naive heroin user, only began taking the drug after they met.

The young mother had taken steps to turn around her life in the weeks before her death, the court was told. She had been staying at a women’s refuge for some weeks before New Year’s Day, and had plans to attend Karralika, a residential alcohol and drug rehabilitation service.

Then something went ‘‘very wrong’’, Director of Public Prosecutions Jon White said.

Her mother received a call on New Year’s Eve from a woman at Narcotics Anonymous, telling her that her daughter was behaving erratically.

The concerned mother went and picked up her three-year-old granddaughter.

The woman ran away from her mother and some time later turned up at the unit of a man she knew, who lived in a block of flats in Reid.

She asked him for enough heroin to end her life. He says he refused, and she slept on his floor overnight.

The next morning, Walmsley came to pick her up, the court heard.

The couple went to her mother’s house where the young mother wrote a will, which Walmsley read in the presence of her mother.

In the handwritten will she wrote that ‘‘in the event of death or disappearance’’ the care of her daughter should be handled by her mother.

She then asked her mother for food and petrol money and left, the court heard.

Later that day, Walmsley went with her to the refuge, where she told staff she had been using drugs and was abandoning her rehabilitation efforts.

They returned to her $500 which she had put down as a deposit onher first weeks of rehabilitation at Karralika.

She later went to a drug user’s house, where the Crown alleges Walmsley helped to organise $420 worth of heroin from a dealer in Gungahlin.

The pair took a small amount of heroin with two other drug users, one of whom noticed that the woman had been ‘‘immediately affected’’.

The drug user warned Walmsley not to give her any more, the court heard.

The pair went back to Walmsley’s flat in Ainslie Village later that night, and the woman asked her boyfriend for some paper and a pen. She wrote a suicide note titled ‘‘my suicide with John’’, which police found crumpled up the next morning.

She addressed the note to her family, writing: ‘‘Please know that none of this is your fault.

‘‘I’m sorry but it’s time to go,’’ she wrote.

The Crown alleges Walmsley and the woman entered a suicide pact and that both took drugs.

It alleges that, at one stage, the accused woke her up to help her take more drugs.

He called triple-0 at 3.25am, saying his girlfriend had overdosed and was no longer breathing.

The Crown alleges it was ‘‘very likely’’ she was already dead at that point.

The triple-0 call was played in court on Monday. Walmsley was heard attempting to perform CPR on the woman for a long time, instructed by the ambulance call taker.

Walmsley has pleaded not guilty and is fighting the charge of aiding and abetting suicide.

He told police after the woman’s death that she had regularly talked about suicide, and said he had tried to take most of the heroin himself to prevent her dying.

Defence barrister James Sabharwal told jurors they should assess the evidence dispassionately, and not view the case using a ‘‘moral censure’’.

‘‘There’s a lot of emotion in this trial, but I ask you to keep your minds open and look at the evidence dispassionately,’’ Mr Sabharwal said.

The Crown noted that an individual had the right to take their life, but that assisting suicide was a crime.

Mr White said laws against assisting suicide were designed to protect vulnerable people and to preserve the ‘‘sanctity of human life’’.

The trial continues before Justice John Burns on Tuesday.

■ Support is available for anyone who may be distressed by phoning Lifeline 13 11 14 or beyondblue 1300 22 46 36.