On April 17, 1984, Yvonne Fletcher, a 25-year-old British police constable, died of a single bullet to the abdomen while standing guard outside the Libyan embassy in London.
The shot came from within the embassy. But her killer remained hidden, first inside the embassy during an 11-day armed siege by police and snipers and then, for the many years that followed, in Libya, where the embassy's staff were spirited after claiming diplomatic immunity.
Ms. Fletcher's death would come to stand with the Lockerbie bombing as one of the signal events in turning the west against the regime of Colonel Moammar Gadhafi. It has also, for many years, remained what is arguably Britain's most important unsolved mystery – one that has led to no charges, no arrests, and a simmering anger that the decades have done little to diminish.
But as the regime that shielded Ms. Fletcher's shooter disintegrates, a Toronto lawyer who quietly helped British police re-examine the case says there is new hope that those responsible will be found and held to account.
"The hope is that there will be increased co-operation, that witnesses won't be afraid to speak and that new evidence can be gathered and then assessed," said Graeme Cameron, a former Ontario Crown prosecutor who, in 2005 and 2006, was secretly asked to pore through the vast reams of evidence and witness statements related to Ms. Fletcher's death. He produced a report on his findings in 2007.
If that happens, "there may be, like the Lockerbie case, the possibility of a trial in another jurisdiction or there may be, under a new regime, the possibility of a trial within Libya," he said.
Yet even if the Gadhafi downfall provides British officials the ability to search for Libyan suspects they have long sought, solving the killing "will require a lot of work," Mr. Cameron cautioned.
Locating suspects may also prove difficult.
"Some of the people who were named in the report grew to be high-ranking officials in the Libyan government," said Mr. Cameron, whose involvement was revealed Friday by The Telegraph newspaper, which obtained a copy of his 140-page secret document.
In it, Mr. Cameron names a junior diplomat who was identified by a witness as the shooter. But in an interview Sunday, Mr. Cameron said he "had grave doubts" over whether enough evidence could ever be assembled to prosecute the person who pulled the trigger.
Instead, he found "overwhelming evidence" of "preconcert and a conspiracy." His report, as quoted in The Telegraph, alleges two others in the embassy took on leadership roles and "advised that the demonstrators would be fired on, directed their positioning outside the bureau and gave instructions as to what they were to do when the firing stopped."
Mr. Cameron was called on to help in part because of his experience in prosecuting complex cases, including against the Hells Angels and the tobacco industry.
Assembling the Fletcher report was, he said, "an enormous challenge. It was a ton of work, very long hours, sifting through every single piece of evidence that had been gathered."
Mr. Cameron declined to specify what, if any, police oversights he was able to uncover. But the initial investigation was complicated by several factors. Evidence was gathered before police could rely on computers to organize findings. In addition, the UK had not yet established a central prosecutors' office, "so the police would get their advice from a variety of people."
Mr. Cameron was able to compile a computerized database of evidence and glean new insights into what happened with the Fletcher shooting, in part by pinning down a more precise sequence of events.
"I guess my contribution was to look at the case in a different way," he said.