Mr Duggan went to Germany to protest against the war in Iraq
The Attorney General has said there is an "unanswered question" over the death of a north London student allegedly involved with a right-wing group.
Jeremiah Duggan, 22, from Golders Green, was found dead on a motorway near Wiesbaden, Germany, in March 2003.
A German inquest ruled that he killed himself but this was subsequently disputed by a British coroner.
Baroness Scotland agreed that the cause of Mr Duggan's death was unclear. His mother will apply for a fresh inquest.
German police said Mr Duggan was fatally injured after running into the path of two oncoming cars in 2003 and a verdict of suicide was recorded.
But later that year Hornsey coroner Dr William Dolman said Mr Duggan was in "a state of terror" when he died and the prospect of a suicide verdict was "impossible".
The coroner's pathologist said Mr Duggan's injuries were consistent with being beaten around the head.
The British inquest heard that Mr Duggan, who was Jewish, had gone to a conference in Wiesbaden to protest at American involvement in the Iraq war.
"I learned he had been sucked into an extreme political organisation," Mr Dolman said.
"He was unaware of the nature of that organisation, it was an anti-American group.
"I have heard evidence that is very disquieting and worrying. In Mrs Duggan's words, her son had been with a sinister organisation that seemed to attract and recruit young people."
The inquest heard that Mr Duggan phoned his mother Erica shortly before he died, saying, "Mum, I'm in big trouble," and, "I'm frightened, I want to see you now."
He also phoned his girlfriend, telling her: "They do experiments on human beings, with computers and magnetic waves."
Mr Dolman told the inquest: "Something had happened that made him run away from the house into the road."
He recorded a narrative verdict.
In 2008 Mrs Duggan won permission to challenge the government's refusal to consent to a High Court application for permission for a new inquest.
On Thursday Baroness Scotland said: "There is an unanswered question from the inquest into Jeremiah's death as to whether the fatal injuries he suffered are in fact attributable to a car accident."
Legal firm Leigh Day, acting for Erica Duggan, said she was very pleased to have the Attorney General's support.
A spokesman for the firm said Mrs Duggan would apply to the High Court for a fresh inquest in a bid to obtain "a just and proper public investigation into her son's tragic and suspicious death".