The integrity of police officers and the departments they work for have come under considerable scrutiny in the past several years. In few cities, however, has that scrutiny been more intense than in Chicago, where reporter Jamie Kalven has broken a number of important and disturbing stories.

Kalven has worked in Chicago for decades as a human rights activist, and across those years he has written about conditions in the city’s public housing, as well as the broader lives of its residents. His reporting on the police killing of Laquan McDonald earned him the 2015 George Polk Award for Local Reporting. Kalven’s dogged pursuit of the details in the shooting death of the 17-year-old turned up evidence of an effort by police to mislead the public.

At The Intercept, Kalven recently published a blistering account of retaliation involving two Chicago police officers who had broken the department’s unofficial code of silence about misconduct within its ranks. On this week’s podcast, we spoke with Kalven about the difficulty of reporting a whistleblower’s tale. Few sources were willing to go on the record. Establishing irrefutable corroborating evidence was difficult, and often impossible. Kalven suggests that journalists may have to set aside some traditional reporting standards in order to tell the stories of brave but vulnerable whistleblowers.

A few highlights from our conversation:

Tell me about the beginning of this story and meeting your lead source, Shannon Spalding.

Kalven: When Shannon Spalding first made contact with me she was just desperate for somebody to believe this elaborate, complicated, in some ways improbable story she was telling of an extortion racket over any number of years by a group of gang tactical officers that was in effect being enabled and protected by high ranking police officials. Once we started talking it was apparent that she was for me, in some ways, the missing part of a puzzle. I had been working for many, many years, going back to years of immersion in public housing when I was working as an organizer, as an advisor to residents, but also as a journalist in that setting, doing what we thought of as human rights documentation.

Really within an hour or two of first talking with Shannon I realized that there were parallels between our experiences, and there were things that I could learn from her that would illuminate questions that I had been trying to make sense of for years as a reporter.

What’s different about telling a whistleblower’s story?

Kalven: I recognize that there's a degree of sort of pushing the envelope with a story like this, but I want to suggest that we have an obligation, not just to the Edward Snowden's, but to whistleblowers whose stories in the nature of things can only partially be corroborated. Take an example: let's imagine that somebody escapes from a criminal enterprise, let's say human trafficking, somebody escapes from a human trafficking criminal enterprise. They've gone through hell, they have a critically important and compelling story to tell. It's the nature of that criminal enterprise to deny its own very existence. Any inquiry will be met with that kind of flat denial. It's also the nature of what this source has undergone that they can't corroborate it very much in conventional ways. Is it appropriate for us not to tell that story? [That’s one of the questions] that we have been grappling with and trying to handle as responsibly as we can, but seeing it as a really different question, a different journalistic occasion than the stories we routinely do where if you need a double source and it's easy to find corroborating documents, and if it's a conversation reported of multiple people to check with everybody else who was in the room. There are some stories that are just critically important stories to tell where that is not going to be possible.

Because so many of the potential sources either opted not to speak to you or provided denials, did you ever question what you were learning from Spalding?

Kalven: Yeah, that's a really good question. I think that's always a tension. The point I made before about needing other eyeballs, you want people to keep you self-skeptical about your reporting. I think you can get kind of entrapped by your own story, and I very much wanted to be challenged on that account. I have to say as it went forward, and I can't count the number of times we circled back with Spalding particularly, also with Echeverria, had to go over a scene again to just be sure that they told it the same way. All of that came out of a concern that could I be wanting this story too much, could I be deluding myself, could I be dialing back my own critical faculties and how I'm proceeding. The accumulating denials, you know, as the denials came in and as I cataloged them in the legal documents, I have to say that actually built my confidence in the story. Because remember this is a story about official denial; this is a story about the code of silence.

Listen to this podcast on iTunes, SoundCloud or Stitcher. For more, read Kalven's series, Code of Silence.