While the documentary does not seek to solve the case of who murdered the sisters, it shows that when they went missing their father was about to testify in a case against an alleged drug lord for whom he worked.
The father decided not to testify against the alleged drug lord, who the documentary showed as having close relationships with local police.
The film has won more than a dozen awards at film festivals around the world, after debuting at New York’s Tribeca in 2011.
Hitting Philippines screens last year, it has become a must-see cautionary tale on the nation’s justice system, with more than 100 law schools around the country having signed up to screen it for their students.
It also inspired the creation last month of the Innocence Project, a network of law schools and students who offer free legal help to convicts using DNA technology and investigative work to overturn wrongful convictions.
“The movie highlighted the defects and imperfections of the justice system,” said Jose Manguera Jose project spokesman and law professor at the University of the Philippines. “There are so many wrongful convictions.”
The Philippine justice system has long been regarded as corrupt, with low-paid judges vulnerable to bribes and intimidation.
The current Philippine president, Benigno Aquino III, has made fighting corruption throughout all part of society the top priority of his six-year term.
Philippine Justice Secretary Leila de Lima was non-committal when asked whether she thought Larranaga was innocent.
“It is difficult to ascertain at this point whether there was a miscarriage of justice,” she said.
National police spokesman Generoso Cerbo declined to comment on the alleged corruption in the police force that was raised in the documentary.
Meanwhile Larranaga, now aged 35, remains behind bars in Spain.
Syjuco said that Spanish justice authorities, after seeing the film, no longer require him to admit his guilt in exchange for early release.
He has also been permitted some trips outside of jail for therapy, including one to a film festival to watch the documentary.
However, he remains ensnared in legal complexities and his final freedom remains far from certain.