The family of a former Harrow pupil mysteriously found dead on a roadside in Germany met in Berlin on Friday to raise awareness of his case.
Jeremiah Duggan's parents believe their Jewish son was unwittingly lured to a conference in March 2003 organised by a right-wing political cult and beaten to death with a blunt instrument.
However, German authorities ruled the 22-year-old student, who went to Quainton Hall School in Hindes Road, Harrow, committed suicide by hurling himself in front of a car.
His parents have fought a five-year battle for the case to be re-opened and met with politicians and scholars at the House of Democracy and Human Rights in Berlin to examine the circumstances around Jeremiah's death.
Simon Hughes, Liberal Democrat MP for North Southwark and Bermondsey, has supported the Duggan family throughout their ordeal and also spoke at the conference.
Hugo Duggan, Jeremiah's father, who lives in Grange Road, Harrow, said: "First of all we were there to raise awareness about our own case which still has never been investigated. Other families affected by the political cult, known as LaRouche, spoke about their experiences and German MPs showed their support for our case.
"Former members of LaRouche gave powerful statements and damning accounts about the group. These people do not normally speak out.
"It was a very positive meeting with people coming together to make sure we are in the process of blowing this far-right organisation away and we will continue to campaign for justice."
Jeremiah was studying in Paris before going to Germany to attend what he thought was a conference opposing the war in Iraq.
In fact it had been organised by the far-right Schiller Institute, inspired by Lyndon LaRouche, a US right-wing conspiracy theorist. Unknown to Jeremiah it had a history of anti-Semitism.
Mrs Duggan, who lives in Golders Green, presented a list of demands at the conference. She said: "I have already lost my son and nothing will bring him back but I believe there has to be a full investigation of Jeremiah's death and its relation to the LaRouche group - or else the danger continues for others."
* For more about the Justice for Jeremiah Campaign visit www.justiceforjeremiah.com