It took the South African authorities four years to get the Anni Dewani case to trial, only for a judge to throw it out after two months.
Shrien Dewani has always denied any involvement in the murder of his wife in Cape Town in 2010.
Here are some of the contributing factors behind her decision.
The credibility of Zola Tongo’s and other witnesses’ evidence:
Zola Tongo was the state’s star witness and agreed to testify against Mr Dewani as part of a plea bargain.
The taxi driver was jailed for 18 years in 2010 for his part in the murder of Anni Dewani and claimed he was paid just over £1,000 to arrange the murder.
CCTV revealed in court showed Mr Dewani and Tongo locked in conversation at the hotel a few days before the murder.
Tongo claims Mr Dewani asked him if he knew anyone that could “have a client of his taken off the scene”.
However, Judge Traverso said Tongo’s evidence was “riddled with contradictions”.
She said he had changed his version of events frequently when under cross-examination.
He admitted he made mistakes in relaying to police how the new bride was murdered.
Judge Traverso said his “evidence was of such a poor quality, one does not know when the lies end and when the truth begins”.
She also said it soon emerged under cross-examination that witness Mziwamadoda Qwabe, who has also pleaded guilty to the murder, was a self-confessed liar.
The evidence of Monde Mblolombo, a hotel worker granted immunity from prosecution, was also discredited.
Evidence about Shrien Dewani’s private life ruled inadmissible:
In a sensational admission at the beginning of the trial, Mr Dewani admitted having physical relationships with male prostitutes.
He also admitted surfing gay dating websites the day after his bride’s body was found.
Veteran South African lawyer, Mannie Witz, who followed the trial, said: “The defence seized on that immediately and said ‘you can’t attack his character and his sexuality’. And the judge said ‘I think the defence are right, I don’t want to hear anything more’.”
The prosecution had been relying very heavily on this evidence and it was a big blow to them when the judge told them this type of ‘character evidence’ was inadmissible.
In court the care home owner from Bristol claimed he was in love with the 28-year-old – despite being bisexual.
But in an interview before the trial, Anni’s sister Ami Denborg said the relationship was up and down.
CCTV recorded on the night she was killed does seem to show a young couple in love.
Their picture is taken by hotel staff and later they sit with their arms draped around each other.
Shrien Dewani’s side of the story:
Mr Dewani, 34, maintained his innocence throughout the case and said he had been suffering from post-traumatic stress disorder since the murder.
The South African authorities spent a lot of time and money arranging his extradition ahead of the trial.
Anni’s family claimed Mr Dewani had insisted throughout the case that he would clear his name and that his legal team had promised the court dozens of times he would give his own version of events.
The family have waited years for answers, but Mr Dewani has never been cross-examined.
Last week Anni’s brother, Anish Hindocha, called a news conference on behalf of his family and begged Mr Dewani to “tell the world what happened the night she died”.
Mr Hindocha said: “My message is simple: Don’t let Shrien Dewani walk away without giving us, South Africa and people all over the world the full story.”
Now that the case has collapsed they may never know the full facts.