On August 31, 2018, I was in the Sheremetyevo Airport in Moscow, waiting for my flight to New York, when I received this text on WhatsApp: “Trevor and Barry had their doors kicked in this morning in dawn raids and are presently in police custody for breach of s5 of Official Secrets Act.”

With a few clicks and a hasty review of a police press release from Belfast, Northern Ireland, I was able to grasp the basics. Trevor Birney and Barry McCaffrey, two producers on a documentary film I had directed, No Stone Unturned, had been arrested and held for questioning for the “theft” of classified documents relating to the Loughinisland Massacre, the subject of the film. The arrests had been noisy. Some 100 police officers, fully armed, had turned up at the homes of Birney and McCaffrey, and the offices of Birney’s company, to take them into custody and confiscate their computers and digital records—everything from company hard drives to personal cellphones.

Russia was an odd place to receive this news. On a trip to meet Putin’s spokesman, Dmitry Peskov, I was carrying a newly wiped Chromebook and burner phone to forestall hacks into my systems either by Russian gangsters or by government spies. But the threat, it suddenly seemed, was not as present in Moscow as it was in the United Kingdom, where police, confronted with compelling evidence of likely suspects in a grisly mass murder, avoided reckoning with the homicides and sought instead to harass filmmakers for trying to reveal the truth. A further call revealed that Birney and McCaffrey weren’t the only ones wanted by the police. There was one other suspect: me.

*

I first became involved in the story when Birney, a Belfast-based producer with whom I had worked on the Irish portion of Mea Maxima Culpa, a film I directed about clerical sex abuse, alerted me to the Loughinisland story. I directed a short about it for ESPN called “Ceasefire Massacre,” but then, intrigued by new clues in the case, I returned for a more rigorous investigation.

On the evening of June 18, 1994, the headlights of a red Triumph Acclaim pierced the twilight of midsummer’s night as it rumbled its way past the paddocks and small farms of County Down, toward Loughinisland (pronounced “Loch-en-island”), some twenty miles south of Belfast. The village itself is little more than a church, a Gaelic football pitch, and a pub, the Heights Bar, where, that night, a group of men huddled around a battered TV set to watch Ireland play Italy in the World Cup. Few expected powerhouse Italy to lose, but, just after half-time, Ireland was leading 1–0. Everyone in the bar was focused on the TV, transfixed by a giddy sense of possibility.

A few minutes later, the Triumph pulled up outside. While one man waited behind the wheel, two men in coveralls and balaclavas burst from the car with automatic weapons in hand. One man held the door, and the other knelt in a military stance in the entryway and opened fire. Bullets from a Czech-made VZ–58 assault rifle tore through the backs of the men watching the TV. Six men were murdered that night—including eighty-seven-year-old Barney Green, the oldest man killed in the Troubles—and five were wounded.

While the Troubles finally claimed more than 3,500 lives, this particular mass murder struck a universal nerve. The victims, from a sleepy small village, were so defenseless, and the killers so ruthless. Witnesses said they heard one of the death squad shout “Fenian bastards” as the shots rang out, and the gunmen were heard laughing as they ran back to their car. The loyalist paramilitary group, the Ulster Volunteer Force (UVF), claimed credit for the attack. While all the victims were Catholic, none of them had any connections with paramilitary or terrorist activity.

Letters of condolence poured in, including one from the Queen and another from the Vatican. The British secretary of state for Northern Ireland, Sir Patrick Mayhew, pledged that the police, then known as the Royal Ulster Constabulary (RUC), “will never give up until the perpetrators of this heinous act are brought to justice.” In following every clue, they would, as relatives were told, “leave no stone unturned.”

That proved an empty boast: no one was ever charged with a crime, despite an extraordinary amount of physical evidence and damning testimony. When families of the victims called for an accounting of the investigation, they learned that much of the evidence and testimony had been destroyed. “I don’t think they ever lifted a stone,” said the widow of one of the victims, Clare Rogan, “let alone turned it.” She and the other grieving survivors came, in fact, to believe that there was a systematic cover-up of the crime, possibly because the RUC was implicated in it.

This is where I came in, moved by the struggle of the families to learn the truth. Initially, for the ESPN short, I had explored the possibility that the killing was part of an effort to sabotage the peace process. But urged on by Trevor Birney, I returned to do a longer film because of emerging evidence that supported the suspicions of Rogan and others.

During the Troubles, the British government tried hard to recruit informants, or “touts,” as they were called, among the paramilitary gangs on both sides of the conflict. Maintaining these sources meant that the state, which represented the rule of law, sometimes had to look the other way as their double agents committed crimes. For the paramilitaries, committing violent crimes such as punishment beatings or even murder often became a rite of passage. For the double agents in their midst—and their handlers—the more gruesome the atrocity, the more convincing their cover.

With our investigation leading us into this murky realm, other themes surfaced. As the film took shape in the cutting room, we began to wonder out loud how a society can best come to terms with an ugly, traumatic past. Given the fragile peace in Northern Ireland, did it make sense to stir up the embers of smoldering sectarian hatreds? This was not just an abstract moral question for us, but a life-and-death issue for some of our potential sources: one police officer we spoke to declined to give us critical information about the likely suspect, not because he wanted to protect the man, but because he was afraid that friends or the families of the Loughinisland victims might seek revenge.

But we, too, were entering a minefield. By collecting intelligence from terrorists engaged in deadly criminality, the state can be complicit in those crimes. And when informants commit murder, the state has an incentive to keep its homicidal secrets hidden from the citizens it is sworn to protect. This raised the biggest question of all: What secrets should the government be able to keep forever? That issue would cause the filmmaking team itself to become a target of the government of Northern Ireland.

In our interviews with the survivors and victims’ families, it was clear that they felt betrayed: they wanted to know what had happened and who had pulled the trigger, and as citizens of the United Kingdom, they felt that their own government was keeping that knowledge secret. To address such concerns, Northern Ireland established in 2000 the Police Ombudsman for Northern Ireland (PONI) to look into past crimes and assess, on a case-by-case basis, whether the RUC had failed in its duty or, worse, been guilty of collusion with paramilitary groups.

On June 24, 2011, the Police Ombudsman’s Office—under the leadership of Al Hutchinson, a former Canadian Mountie—published a report on Loughinisland that largely exonerated the RUC. Clare Rogan and the other family members reacted furiously to what they saw as a whitewash—and they succeeded in getting the report quashed. A new ombudsman, Michael Maguire, was appointed and opened a new investigation. Maguire was working on this report while we were filming; he declined to cooperate with us, and we feared that his investigation could simply be a repeat of the first.

It was immediately clear from our research that the original 1994 RUC investigation of the murders was either staggeringly incompetent or intentionally bungled. During the Troubles, it was common practice for terrorists to torch their getaway vehicles to eradicate potential forensic evidence such as fingerprints, footprints, and hair. But remarkably, in the Loughinisland case, both the car and weapons were recovered—along with DNA evidence that would connect to one of the suspects. Even more astounding, the car was found in a field a stone’s throw away from the family home of the chief suspect.

Despite that fact, not a single RUC officer bothered to knock on the door, much less search the place, immediately after the crime. Once the initial phase of the investigation was completed, all of the interrogation logs—along with the car—were destroyed. When the leading suspect was finally arrested, he had already received a tipoff from the police the night before, enabling him to dispose of any incriminating evidence.

Trevor Birney, himself the son of an RUC cop as well as a veteran reporter on the Troubles, was producing my film. In October 2015, Birney called me to say that he had a “walk-in,” a whistleblower with critical information: a former RUC officer named Jimmy Binns who had been involved in the Loughinisland investigation and present for the questioning of the prime suspect. In an on-camera interview, Binns revealed that the “interrogation” of the suspected shooter had lasted only ten minutes, with a handful of laughably perfunctory questions: “Did you do it?” Answer: “No.” Then, according to Binns, the detective in charge of the interrogation spent the next ninety minutes or so trying to persuade the suspect, a known member of the UVF, to commit another killing—of a local IRA gunman.

Binns also related how his superiors had directed him to stay away from certain witnesses and lines of questioning that might lead to arrests of the actual perpetrators. Last, Binns shared details that led us to believe that the Special Branch, the intelligence division of the RUC, may have known about the attack in advance. (Many of the details in Binns’s testimony would later be confirmed by the Maguire report.)

Further evidence came from our visit to Patsy Toman, a retired local councilor. A few months after the massacre, he had received an anonymous letter written in longhand that began: “Dear Mr. Toman, I am writing you to advise you of certain facts… in your quest to cage the Loughinisland murders [sic].” The letter went on to reveal that “the gunman was one Ronnie Hawthorn, a married man from Clough. Gunman Two was Alan Taylor, single from Dundrum. The driver of the getaway car was Gorman McMullan, a convicted terrorist from Belfast…” This document, which had been turned over to the police in 1994, contained other extremely significant details, including a confession that the author was involved in planning the crime but “pulled out of the attack due to a prior engagement… this information will somehow ease my conscience, but will never fully clear my name. But I do this for the family and children of the men who were slaughtered in Loughinisland.” None of the men mentioned above has been charged, and none has had the opportunity to present a legal defense against the allegations.

Thanks to the letter, we had names of potential suspects—and one, Hawthorn, matched the name of the man whose interrogation Binns had observed. But for official confirmation, we would have to wait for Maguire’s report. While Maguire had declined to share any information with us, he did give us permission to film his presentation on June 8, 2016, of the PONI Report to the families of the victims. When he addressed the crowded oak-paneled room in the Loughinisland Athletic Club, he said, “I have no hesitation in saying that collusion was a significant element in relation to the killings in Loughinisland.” As he paused over the word “collusion,” there were audible gasps from the crowd. Some began to cry: they had waited nearly twenty-five years for any official recognition of their pain—now the UK government was finally acknowledging its complicity in the massacre. The collusion Maguire detailed included the supply of weapons to the terrorists and Special Branch’s secret knowledge of the death squad.

*

In the wake of the announcement, Birney, McCaffrey, and I retreated to an office in Belfast with a copy of the report to dig into the details. But we still had one other vital source. A few months earlier, McCaffrey had opened his mail to discover a plain envelope with no return address. Inside was a photocopy of an early draft of the first PONI report on Loughinisland. This draft did not contain the whitewashing conclusions of that first report and it gave far more forensic detail. Last, and most important, it was unredacted. All the names of the suspects and their dates of interrogation were revealed.

This was the document that would cause the police to send some 100 officers to arrest Birney and McCaffrey for its “theft.” It was also the key to understanding the original cover-up.

In Maguire’s report, both suspects and police officers were identified only with letters or numbers, but with the leaked copy of the draft PONI report, we were able to correlate names and dates and crack the code. What emerged was a remarkably detailed account of collusion and cover-up, as well as confirmation of the names of the prime suspects. The author of the anonymous letter was revealed: Hilary Hawthorn—the wife of the man she had named as the gunman. Why would she turn in her own husband? In her letter, she claimed it was her sorrow for the victims. In fact, we later learned, she had ratted out Ronnie when she discovered he was having an affair.

In 1994 the police had twice arrested Ronnie Hawthorn for questioning but never charged him. But more damning, Hilary had also been questioned and admitted to the police that she was the author of the letter. As a confessed accessory, why hadn’t she been charged? Or why, at the very least, hadn’t the police used her information to compel cooperation from her husband (with whom she had by then reconciled)?

For answers, we sought out one of the officers involved in the investigation. The name of the detective who had questioned the suspects, Albert Carroll, appeared in the leaked report. He refused to be interviewed on camera, but he did confirm to us crucial details contained in the documents. When asked why he let Hilary go so quickly, he said she was a “proper lady,” from a “nice background.” In fact, she worked at the nearby Newcastle police station, which was assisting in the murder investigation. Carroll told us that he decided to let her and her husband go only on the strength of Hilary’s “cooperation” that would hopefully “ensure that Ronnie would never kill again.”

There was another question to answer: Among the Loyalist killers, had there been an informant? By cross-referencing the Maguire report with the draft PONI report and some information from Niall Murphy, the attorney for the survivors and victims’ families, we concluded that the three named suspects were part of a four-person gang that had likely committed other murders in the County Down area. Through legal disclosure, Murphy told us that one of the four men was an informant for the British government at the time of the Loughinisland Massacre. Another document we obtained suggested that two of the four had been touts. Finally, we were able to obtain government confirmation that the gang had included at least one informant.

Just before the film’s final edit, we offered the named suspects a “right of reply,” sent by registered mail; our letters went unanswered. We informed the Ombudsman’s office of the likely suspects the film would name. PONI then passed that information on to the Police Service of Northern Ireland (PSNI), the successor to the RUC. We wanted to be sure the PSNI was informed in case there was any concern for the safety of the suspects or in case the police had any other compelling reason why the film should not be released. We received no response.

No Stone Unturned premiered at the New York Film Festival in 2017, and shortly thereafter at the London Film Festival; it went on to receive a successful theatrical release in Northern Ireland and the Republic of Ireland. The film made waves in Northern Ireland and the Republic of Ireland, where discussions resumed about how to reckon with the past. There was no official government reaction to the release.

*

I had never intended the film to be a relitigation of the Troubles. In fact, I purposefully avoided the theme of sectarianism and treated the murders simply as a cold case in the hope that, if we could come close to identifying the suspects, it could bring some salve to the psychic wounds of the survivors and families of those who had been killed. I also hoped that the film might spur the police to investigate, properly this time, the mass-murder it could have solved but deliberately didn’t.

Certainly, the police should have been embarrassed into acting. Investigators had had all the suspects in custody, had physical evidence, including DNA, the murder weapons, the getaway car, intelligence linking the suspects to a chain of prior murders, and a written confession from one of the conspirators. Then there was the destruction of evidence, the refusal to acknowledge how much was known, and the concealment of government collusion. Since the release of the film, however, there has been no move by the police to bring the killers to justice. Instead, last August, we saw a major police operation to punish and silence the messengers.

Following their arrest, Trevor Birney and Barry McCaffrey were held for questioning for fourteen hours. After they were released on bail, Birney told me that the potential charges were: theft of government documents, the disclosure of the whereabouts of a police officer, and violation of Section 5 of the Official Secrets Act. When I hired my own lawyer, he told me that stealing confidential information (as opposed to computer records) is not an offense as you are stealing a piece of paper (which has no value) rather than what is written on it. In revealing the whereabouts of Detective Albert Carroll, there is only one guilty party: the French telephone book, which is where McCaffrey found Carroll’s address. But Section 5 of the UK’s Official Secrets Act is a serious charge that allows for the prosecution of newspapers or journalists who publish secret information leaked to them by a crown servant or government contractor, and it can carry a two-year prison term.

There were other odd aspects to the arrests. Although PSNI officers carried them out, the PSNI was not officially in charge of the investigation. In cases of political sensitivity, the PSNI calls in an external police constabulary—in this case, from Durham, England—to reassure the public that the police aren’t improperly investigating themselves. The precedent stems from an instance in 1999, when a solicitor named Rosemary Nelson raised questions about police collusion before US Congress. Shortly after she complained that local police were threatening to kill her, she was murdered.

In our case, the police claimed that they were pressed into action by a complaint of “theft” from the Police Ombudsman for Northern Ireland. But Michael Maguire confirmed to me that PONI had never made such a complaint. To date, no charges have been filed but Birney and McCaffrey are still restricted by terms of bail—they must, for instance, ask permission to leave the country. I, also, must inform the Durham police of any entry into the UK, in case there is a desire to question me.

In challenging the search warrants, Birney’s lawyer, Niall Murphy, who also represents the Loughinisland victims’ families, accused the PSNI of using a dramatic show of force as a kind of warning shot to other journalists who might want to investigate police corruption or criminality. There’s no doubt that it’s part of a global trend of governments harassing, prosecuting, and even murdering journalists who expose state secrets. In the United States, where our president has called the press the “enemy of the people,” the CIA has fought a bitter battle against reporters and filmmakers to prevent any accountability for the agency’s failure to prevent September 11 or for the likely crimes of its post-September-11 torture program. Myanmar, a former British Territory, used its own Official Secrets Act to jail two reporters for seven years over their reporting of a government-backed massacre of Rohingya Muslims. Two Russian journalists and a filmmaker were murdered recently while investigating the alleged involvement of Yvgeny Prigozhin, known as “Putin’s chef,” in mercenary operations in the Central African Republic. And most notoriously of all, there was the Saudi writer Jamal Khashoggi, assassinated and dismembered in the Saudi embassy in Istanbul by agents of Crown Prince Mohammad bin Salman, a favored ally and friend of the Trump administration. A total of fifty-three journalists were killed last year for doing their jobs.

It’s hard to know why the police waited for a year to burst into the homes of Birney and McCaffrey, but I can guess at reasons for such a display of force. They may have hoped to intimidate McCaffrey into revealing his source—though he has said he has no knowledge of who sent him the draft report. More likely, the police may be acting on behalf of British intelligence and security services, which have little patience with being held to account for past crimes and want to send a message.

As if to underscore this point, the Police Service of Northern Ireland recently informed the ombudsman’s office that it had withheld as many as 13,000 pages of police records that PONI had requested for another investigation into murders tainted by possible collusion, a 1992 attack by Loyalist paramilitaries on a bookmaker’s shop in Belfast that killed five people. While the PSNI has blamed the failure on clerical errors, Niall Murphy sees evidence of “dark forces” determined to keep government misconduct hidden from the public. Murphy also claims that these records relate to the same shipment of weapons—from South Africa, arranged by a British agent—that were involved in the Loughinisland case. “These VZ–58 weapons had never been in this jurisdiction before ever,” Murphy told the Belfast Telegraph this month. “They would then go on to kill over seventy people. The arms importation that had Browning handguns, grenades, rocket-propelled launchers would go on to kill 229 people.”

The Loughinisland story matters because it raises universal questions about how societies reckon with the past, particularly when that history involves crimes committed in an internal conflict. Many people in North Ireland and the Republic of Ireland are anxious, with good reason, not to revisit the Troubles. It may be that in the wake of the Good Friday Agreement, there was little stomach to re-investigate Loughinisland lest the cause of justice upend the delicate balance of peace.

Today, with the specter of a hard Brexit, Ireland and Northern Ireland may have to return to an old paradigm and “build a wall” between the two countries where the current marking of the border is nothing more than a sign on the highway. That prospect is already inflaming tensions between paramilitary groups—Irish nationalists and loyalists alike—which retain many of their weapons.

With that prospect, the willful denial of past crimes can be a first step down the road to perdition. Government officials argue against disclosing secrets because it may expose sources and methods. But in the long run, transparency is vital for democracies to ensure that mistakes are not repeated and misdeeds not overlooked. Intelligence services always resist declassification and reappraisals of covert operations lest they undermine the morale of those who put themselves at risk to protect the citizens they serve. But what about the morale of all those who observe the rule of law yet see those who subvert the rules to deadly effect never held to account?

In the case of No Stone Unturned, the police—or whoever is issuing the orders on which the police are acting—have fired a warning shot aimed at those who are willing to reveal dirty secrets and tell uncomfortable truths about government informants and handlers involved in past atrocities. From the perspective of the government, keeping secrets is the price of law and order. But from the perspective of victims and survivors, a secret that hides the truth is not any kind of justice; it means getting away with murder.

No Stone Unturned can be viewed worldwide on Amazon Prime.