Former prostitute Emma Humphreys, 30, originally of Dolgellau, North Wales, was found dead in her London flat in July this year. She had died of trichloroethanol poisoning.

Three years ago she was released from a life sentence for killing her violent pimp Trevor Armitage, having spent 10 years in jail for murder.

Her supporters said she had accidentally overdosed on chloral hydrate, a sleeping medication, to which she had become addicted while in prison.

Prescription concern

Patrick Roche, the lawyer representing her father John, argued that the case should be heard in front of a jury because of the high levels of chloral hydrate prescribed after her release by her doctor.

He said other patients could be at risk in a similar situation.

Katie Gollop, representing Ms Humphreys' GP Dr Mayur Gor, said the case did not need to be held in front of a jury because the doctor was not prescribing the drug to anyone else.

But the coroner at St Pancras, central London, Dr Stephen Chan, said: "I believe it would be right for me to exercise my discretion in this very tragic case and to direct the inquest to be heard in the presence of a jury."

He also agreed to allow the evidence of a pharmacology expert to be heard.

After the hearing Mr Humphreys said he welcomed the coroner's ruling. "I'm very pleased. It is the only right decision. Obviously the main thing is to get to the truth, to find out exactly why Emma was prescribed such a high dosage of chloral hydrate."

A date for the full hearing has still to be set.

Years of abuse

Ms Humphreys had suffered abuse at home and was put into care before becoming involved in drugs and prostitution in her teens.

Armitage was a former client and had previous convictions for violence.

Years after her conviction, it was revealed that he had subjected her to months of severe physical, sexual and emotional abuse.

She finally stabbed him when she thought he was about to attack her again - but did not tell the murder trial about her treatment at his hands.

It was only in 1992, after other similar cases hit the headlines, that Ms Humphreys contacted a support group and told them about her case.

In 1995, the Court of Appeal reduced her conviction to manslaughter and she walked free to be greeted by a crowd of cheering supporters.

Her case created a significant legal precedent, but Ms Humphreys reportedly found it difficult to adjust to life outside prison.