The family of murdered aid worker Margaret Hassan spoke today of their hopes that a trial in Iraq this week will end their desperate quest to recover her body.

Mrs Hassan, 59, the director of aid agency Care International in Iraq, was kidnapped on her way to work in Baghdad in October 2004 and shot dead just under a month later.

Her family has spent the past four-and-a-half years trying to discover where her remains are so she can be brought back to Britain for a Christian burial.

An alleged member of the kidnap gang, Ali Lutfi Jassar, is due to stand trial at Baghdad's Central Criminal Court on Tuesday. He is accused of attempting to blackmail Mrs Hassan's family for millions of dollars in return for telling them where her body is.

The aid worker's sister, Deirdre Fitzsimons, said she understood he was now denying all knowledge, but she is clinging to the hope that he will reveal the truth if he is convicted.

"If he's put in prison, if he knows he's got a life sentence, maybe he will decide to tell us where her remains are," she said.

"I don't believe we are ever going to get justice for my sister. But we would like her to be buried here because my family has suffered over the past four-and-a-half years. We have spent all our time trying to find her remains. We want some peace in our lives."

Mrs Hassan was one of the highest-profile figures to fall victim to the wave of kidnappings that swept Iraq after the 2003 US-led invasion.

The Dublin-born Roman Catholic, who had joint British, Iraqi and Irish nationality, was married to an Iraqi and had lived in Iraq for 30 years.

So far only one person has been brought to justice over her abduction and murder.

Mustafa Mohammed Salman al-Jabouri was sentenced to life by a Baghdad court in June 2006 after being convicted of aiding and abetting the kidnappers. His sentence was later reduced on appeal.

Ali Lutfi Jassar was arrested by Iraqi and US forces in August last year after allegedly contacting the British Embassy in Baghdad and attempting to extort money in return for leading them to Mrs Hassan's remains.

Ms Fitzsimons said the transcripts of his communications with Embassy officials showed that he mentioned an intimate detail about the aid worker that only her closest family and friends knew.

"That shows he had been with her. He was part of this gang," she alleged.

Jassar was brought to court with a second man in December last year but the case was adjourned.

Ms Fitzsimons said: "We want to ensure she gets buried with the respect she deserves because she has not been treated with respect. My sister was a Catholic and it would be her wish to have a proper Christian burial.

"However much she loved Iraq, she always wanted to be buried in this country. That is what we want to do for her. We don't expect justice but if we can just do that for her, that would be helpful for us and our brother-in-law."

A Foreign and Commonwealth Office spokeswoman said: "Any ongoing investigation and trial is an Iraqi lead. We will continue to work with the Iraqis as they continue their investigation into Margaret's kidnap and murder."