“It’s like the airport shuttle from hell.”

That’s how Zachary Raines described his experience as a guard escorting inmates to jails and prisons around the country to Marshall Project reporters Eli Hager and Alysia Santo.

Raines was one of some 50 current and former guards who spoke to Hager and Santo for "Inside the Deadly World of Private Prisoner Transport," a devastating examination of the for-profit van companies used by prisons to transport inmates. The reporters found that a dozen prisoners died in such vans in the last 16 years; a dozen more suffered serious injuries; at least 60 managed to escape, and many alleged sexual and physical abuse at the hands of drivers and guards. This week the reporters join the ProPublica podcast to tell us how their effort grew from a tip on one prisoner who was beaten to death to a full and rare examination of a dangerous, virtually unregulated industry.

Here are some highlights from our conversation:

Sapien: Who is Steven Galack?

Hager: He was a father of three. He formerly owned a home remodeling business. He was a successful middle class businessman, but he had a bit of a downfall. He had a divorce. He had to move to Florida. He had a painkiller addiction at one point and suffered from extreme anxiety. Anyway, he got behind on his child support, and an arrest went out from Ohio where he used to live, and at one point he had an interaction with police in Florida, and they saw this warrant in Ohio, and essentially Ohio hired this private company, PTS, to go pick him up in Florida and drive him to Ohio. He got on the van after some days at the local jail there. It was extremely hot. It was in the 90s in late July.

At one point, according to two of the prisoners, the one driver of the van pulled over, took Steven Galack out, put him in, thrust him in the middle between the other prisoners and said, "Only body shots, have at him" basically suggesting that they beat him to get him to shut up. Seventy miles later after they had crossed into Tennessee, his body was found. There was blood, urine, and vomit on the van. He had a broken rib. He had a chipped tooth, cuts all over his face, bruises on his body, and he was dead, but the homicide investigation lasted less than 24 hours, and the van just went on its way with all the passengers on board, and no one was ever re-interviewed.

Sapien: How did you get from Steven Galack's case to what sounds like a pretty voluminous array of cases?

Santo: We had a few different methods. We pulled as many lawsuits as we could and organize the allegations of the lawsuit into different kinds of categories of abuse and neglect occurring. Another aspect of our story was escape and crashes. Those were really ... Our reasons on those really speak to the importance of local news reporting because we use a lot of news searches to identify these escapes and these crashes that had happened all over the country, and little newspapers would write about them, but there wasn't anybody that had really connected the dots in terms of it's happening. The escapes and crashes were happening all over the place. It was just being written about in little news blurbs, and so that was another really big aspect of our reporting was using those initial news reports and then following up, getting the accident report from the actual agency to find out, for example, what time it occurred and if people were in seat belts.

Sapien: Is there a key takeaway that you guys really hope readers will have after going through your story and listening to this podcast?

Santo: I'm just excited that people know that this exists because I think that that was one of the biggest things for us is that it just seems like one element of privatization in criminal justice that just wasn't ... There was really no attention being paid to it. It is so invisible because they are on the road. They are driving, and it's not like a facility that you can look at and see, and so I think that that is just important in itself that people realize that this is out there, and we put out a reporting guide, and we are hoping that other reporters will dig into it in their own area because, as journalists, we all think, and I'm sure we would all agree, that more attention, more transparency, more light shown on this, then it likely could have an effect if the attention is sustained and we continue to make sure ... People know that it's being watched.

Listen to this podcast on iTunes, SoundCloud or Stitcher. For more, read the story, "Inside the Deadly World of Private Prisoner Transport."