FILE--A Muslim prisoner sits in a sleeping room in the Trnopolje detention camp, near Banjaluka, some 12 miles northwest of Sarajevo, in this Aug. 12, 1992, file photo. Fifty years after the Geneva Conventions outlined the laws of war in the aftermath of World War II, a group of combat correspondents and legal scholars has written a guide to the ways fighting men have broken those codes of conduct.  (AP Photo/Today London, David Cairns, File) UK OUT

Muslim prisoners in a room in the Serb-run detention camp at Trnopolje, northwest of Banja Luka, Bosnia, on Aug. 12, 1992.

Photo: David Cairns/Today London via AP

How do you investigate human rights abuses at detention centers that are off-limits to outsiders?

I am not one of the on-the-ground reporters covering the Trump administration’s abusive treatment of immigrant children on the border with Mexico, but more than 25 years ago I investigated the concentration camps where Serbs tortured and executed Muslims during the Bosnian war. I can’t quite believe that I am writing this line and this story, but much of what I saw at those Balkan camps in the 1990s is relevant to what’s happening now in America.

It appears that due to a burst of media attention, the conditions of the U.S. border camps will likely be improved — there will be soap, toothpaste, and bedding — and journalists are being allowed to visit though in sharply restricted ways. This is a script we have seen before. After the first stories about Serb-run concentration camps were written by Roy Gutman, based on testimony he collected from survivors, the camps were cleaned up a bit and some journalists were allowed inside. I was among the first visitors in the summer of 1992, and what follows is a guide to help journalists understand and thwart the U.S. government’s likely cover-up of abuses that have occurred at its concentration camps. That’s another sentence I can’t believe I am writing today.

Tours of detention camps are public relations tricks; governments do their best to make sure journalists don’t actually visit the exact places where crimes occurred. Here’s an example from Bosnia. One of the worst prison camps was at a ceramics factory known as Keraterm, and I was taken there. Except I wasn’t, really. Keraterm had a lot of buildings, and the group I was with — about a half-dozen journalists — was taken to just one building. Our guide – a brute of a man named Simo Drljaca, who was killed when NATO troops tried to arrest him after the war — walked us into the building, which was mostly empty and had a thin layer of dust on the ground and not a human smudge mark on its floors or walls.

“See, no blood,” Drljaca smiled at us.

His ruse was transparently ridiculous — the building had never held prisoners. We demanded to see the building that we knew had housed prisoners; it was a brick warehouse less than 50 yards from where we stood. Prisoners had been tortured and executed there, and as we later learned, the survivors were moved out shortly before we arrived. No, Drljaca said, it’s a military facility, you can’t go inside or take pictures of it. He instructed us to get back into the minibus we were traveling in. But there were no military vehicles or soldiers in sight. The factory grounds were deserted.

The lesson is quite obvious and simple: You must go to the exact location where abuse has occurred. If you are prevented from going there and seeing what you need to see — a quasi-admission that a forbidden crime scene exists — demand to know why. The lies offered by prison officials can be nearly as revealing as the incriminating evidence kept out of view. Often that’s the only evidence of guilt you might get — the absurdity of the deception.

We were taken to two detention centers that held actual detainees. One of them was called Omarska, which has become infamous over time as the site of the greatest number of killings, and the other was called Trnopolje, which didn’t have as many killings but was nonetheless a location of immense fear and deprivation. Both camps were somewhat cleaned up for our visit, but terror can’t be erased so easily. These visits introduced us to the ethical dilemmas of interviewing detainees who feared repercussions for talking with us, though it also revealed ways to get around those repercussions.

If prisoners are afraid — as all of them were at these camps — you know it instantly. It is in their faces, their voices, their postures, the words they are afraid to speak to you. One of the most chilling moments occurred as I watched a prisoner at Omarska shiver in terror as a television reporter asked, with a camera running, whether he had been abused. The prisoner didn’t know what to do; the truth could’ve gotten him killed by the guards. His inability to say what he wanted to say was a silent form of testimony about crimes that were, at that moment, literally unspeakable.

It’s not a stretch to think that some kids at the camps run by U.S. Customs and Border Protection might be hesitant to complain about abusive conditions, assuming they are even allowed to speak to reporters (so far, apparently not). They might have the same sort of fear as the prisoners in Bosnia — could they be punished for what they say? A workaround to this quandary emerged during my visit to Omarska. One of the prisoners slipped a note to one of the other journalists, who shared it with me. “About 500 people have been killed here with sticks, hammers and knives,” the note said. “Until August 6, there were 2,500 people. We were sleeping on the concrete floor, eating only once a day, in a rush, and we were beaten while we were eating. We have been here for 75 days. Please help us. ”

The lesson from this — beyond the fact, now amply proved by war crimes trials, that Serbs committed genocide in Bosnia — was that it can be far easier for detainees to write something down and surreptitiously hand it to a journalist than to take the more intrusive route of talking to you. I wish I had been armed with pencils and pieces of paper and handed them out, as discreetly as possible, to prisoners who indicated any inclination to write notes, or just left these things in a corner for any prisoner to write a message that might later be given to other sympathetic visitors.

Another suggestion for journalists who might be visiting the CBP camps: Pay close attention to the CBP officials, and not just the polished spokespeople. What is the expression on their faces? Will they answer questions, even banal ones? The pursed lips of guards or supervisors can itself be evocative manifestations of power. They can withhold everything, whether it’s toothpaste, blankets, or words. It’s worth your time to persist with questions until the end. At Omarska, I tried to strike up a conversation with a guard who was nonresponsive until I gave up hope and provocatively blurted out what I wanted to know: “Is it true that you torture the prisoners?

He glanced down at me — he was huge and had pistols on both hips in addition to an AK-47 slung over a shoulder — and his face lurched into a smile that was intentionally and sardonically grim. “Why would we want to beat them?” he said.

Indeed, it appears that U.S. officials are beginning to follow the footsteps of Serb authorities in Bosnia. Just read this chilling story by Simon Romero, who yesterday visited a CPB camp for children in Clint, Texas. The tour for journalists, Romero wrote for the New York Times, was conducted after the number of kids at the facility was greatly reduced. The tour was brief and “highly controlled,” with CPB officials pointing out food and sanitary supplies that they said were being provided to the children — but the journalists were not allowed to enter the cells where the children lived, talk to any of them, or take pictures (their cameras and phones were not allowed inside). When a reporter saw a young girl crying, a CPB agent quickly warned, “Don’t talk to her,” adding, “If you ask her anything you’ll be thrown out.”

A final lesson from Bosnia: The full truth of what happened at the camps did not emerge as a result of journalists visiting them after the worst crimes had been committed. There is a limit to what you can learn at a crime scene that has been cleaned up, and of course there’s a huge limit to what witnesses can tell you in the presence of their tormentors. The truth emerged from later interviews that journalists and investigators conducted with survivors who were able to speak freely in safe locations, usually refugee camps. Tracking down these survivors and taking the time to hear their grim truths was hard work, but it made the difference. Find the families who were kept in abusive conditions at the CBP camps. They know what happened.

I could go on — and it is horrifying that I could go on. How could genocidal events a quarter-century ago have any relevance to America today? That is where we are. That is what we have become.