The twin sister of Mary Boyle, Ireland’s youngest and longest missing citizen, will travel to Washington D.C. this St. Patrick’s Day to campaign for justice for her sister.

Ann Doherty’s battle for the truth began when her 6-year-old twin sister, Mary Boyle, went missing in March 1977 on her grandparents' remote farm in Cashelard, Co. Donegal. Her remains have never been found.

Doherty believes Mary was sexually assaulted and murdered by someone she knew and that her body was dumped close to where she went missing. She also believes she knows who is responsible for the horrible crime, but that political intervention early in the police investigation attempted to cover the killer’s tracks, leaving the perpetrator to walk free.

Meeting with Irish-American politicians, lobby groups and organizations throughout the week, Doherty will inform members of the United States Congress that Mary's killer is being shielded by An Garda Síochana (the Irish police force) and that a politician interfered in the investigation shortly after the murder, ordering that certain people were not to be considered suspects.

“The key purpose of this trip is to open Irish-America's eyes and the US authorities to the wide scale corruption in the Irish police and the criminal justice system,” said Ann Doherty.

“There are many horrific cases of cover-up by the gardaí in the Republic that Irish-Americans and anyone who proclaims to care about Ireland need to know about. The police have protected my sister's killer for almost 40 years.

“I know who murdered Mary. He is walking around Donegal today, immune from prosecution. Instead of arresting him, the gardaí have targeted me, and others who have stood up for Mary's right to justice, in what can only be called an insidious campaign of intimidation.”

Doherty will be accompanied on the trip by award-winning investigative journalist Gemma O’Doherty. Meetings will take place with US Congressman Brendan Boyle, whose father comes from Donegal, with former US Congressman Bruce Morrison, and the group will attend a number of St. Patrick’s Day engagements that will include the Taoiseach (Irish Prime Minister), Northern Ireland’s First Minister Arlene Foster, Northern Ireland’s Deputy First Minister Martin McGuinness and the Irish Ambassador Anne Anderson.

Doherty will brief the National Center for Missing and Exploited Children and the Ireland Fund about the case, as well as a number of organizations that lobby on justice issues.

She has met with the current Taoiseach Enda Kenny once before, in November 2015, and has spoken on her sister’s behalf in the parliaments of Stormont, Brussels and Westminster. Despite these meetings, Doherty feels she is still being met with reluctance to begin a proper investigation into her sister’s death.

Although Enda Kenny received information on the murder in 2011, including the further evidence revealed by journalist Gemma O'Doherty in which people in the area who knew Mary have identified a killer, the Taoiseach admitted he did not follow up on the information after passing it onto the Gardai.

“It is appalling that I have to leave Ireland to try to get justice for my sister,” Doherty said.

“The Gardaí have sufficient evidence to bring her killer to justice, but to do so would reveal a sordid conspiracy between police and politicians.

“No country can call itself a democracy when its police force perpetuates the cover-up of a child's rape and murder. That is why the rest of the world must know about Ireland's record when it comes to policing, justice and protecting its children.”

During her visit, Doherty will also call for the resignation of Garda Commissioner Noirin O'Sullivan and Justice Minister Frances Fitzgerald for failing Mary Boyle, her right to justice, and the public interest.

In December 2015, Ann asked An Garda Síochana for a search of a location in Donegal where she believes Mary's remains may be. Her request has been ignored.

She has also been denied the right to an inquest into her late sister's death.

This case is just one among the many stories of police corruption undertaken by investigative journalist Gemma O’Doherty, who previously worked on revealing the Gardaí penalty points scandal and the cover-up in the murder of Offaly priest Fr. Niall Molloy in 1985.

Following her success in exposing corruption in the Molloy murder case in particular, other families began to contact O’Doherty asking for her help.

Because the Irish authorities were refusing to deal with their cases, she organized a series of visits to foreign parliaments, first traveling to the Northern Irish assembly in Stormont before meeting with MEPs in Brussels.

All of the Irish MEPs met with the families and were struck by their testimonies. They wrote to the Minister for Justice Frances Fitzgerald but their calls fell on deaf ears.

Jeffrey Donaldson MP took the families to Westminster for a series of meetings in September 2015, and now they have decided to take their cases to Washington.

There are plans to visit the Vatican later in the year.

"We have seen scandal after scandal in an Garda Síochana in recent years, and the treatment of officers who are whistleblowers trying to improve the force has been deplorable," said O'Doherty.

"Former Garda commissioner Martin Callinan called the two brave officers who exposed the penalty points scandal 'disgusting'. Sadly, his successor Noirin O'Sullivan has done little to enhance public trust in the force either.

"When gardaí do wrong, there is no oversight or accountability. Many in the media are also afraid to tackle wrongdoing or corruption in policing often because of close links they have with the force, so the public are not being told the truth about issues of huge importance such as the cover up of serious crime.

"I work with a lot of bereaved families who have lost loved ones by homicide and who believe they have been denied a fair and effective investigation by the gardaí," she continued. 

"Their right to justice—a basic human right—is being trampled upon and they have had to travel to foreign parliaments to try to raise awareness about their cases.

"No family who has suffered such a loss should be put through that.

"Any Irish American who claims to care about Ireland needs to be aware of some very serious issues back home, especially when it comes to dysfunction in the criminal justice system."