Brendan McCarthy spent a year and a half covering crime in New Orleans, when a police ride-along sparked an idea for a narrative piece about a murder in the Big Easy. The last part of the acclaimed series was published this Sunday.

How did this story come about?

I cover crime and we have a strained relationship with the police force. They said that their solved crime statistics were improving and they wanted us to do a story.

And we said, “You have to let me show people how you do it. If we tell it and just give them a couple of numbers, it won’t have as much impact.”

They paired me up with these two young detectives for three days with this handshake agreement: I would get to watch them work a case.

The agreement with the cops was this: You work this case two days straight, you eat tuna fish sandwiches, I eat tuna fish sandwiches.

This took a bit of cajoling and there were many people against, and the detectives were very wary of me at first.

On the second day, we’d been together all day, we’d just left the homicide office to go home for the day and then we got the call that the homicide had happened.

They worked this case for 40 hours straight, and shortly after I called my boss and I said we got a lot of stories here.

In this 40-hour span with the detectives, there was so many details, and dialogue and action. There was a point where they were just detectives and I wasn’t in the back seat anymore. I filled twelve notebooks with stuff.

Did it feel a little morbid waiting around for something to happen?

We average a murder here every day and a half. Unfortunately, these things are somewhat routine.

Talk about your reporting with Pardo and Wischan, the two detectives, and the family of the murder victim Lance Zarders.

I was there. I stood there and listened, but I wasn’t allowed inside the yellow tape. I was in the back seat of the car. I wasn’t allowed in the interview room, but I would stand around and catch dialogue as they went in and out. I listened as they talked. They go back and forth with each other a lot and they talk out the case. They also have meetings with their boss, and then I went back and interviewed them afterward.

I did the same things with the family. I went to the funeral and went back to the family.

How much planning was there to do this multi-part, multimedia feature?

We didn’t have a plan at all. We thought we could get a decent Sunday feature out of this, but then this story unfolded on my watch and it begged to be told. We had a photographer on and off for the ride-along.

Why did you chose to tell this story as a narrative?

You pick up the paper on any given day and you see the inverted pyramid homicide story. I’ve written a hundred of those.

With this piece, there was a back-story and a lot of nuances to it that really helped to explain crime and culture. All these little things that were paragraphs in a daily story could be explained.

I’ve written about the security cameras half a dozen times, but now it’s a couple of paragraphs in the story, but it’s a lot more compelling.

I keep on saying we just got lucky here. We didn’t want to stumble over ourselves to tell the story. We just wanted to let it rip.

What sort of guidance did you get from your editors?

Talking to my bosses, they just said write it as you see it. They’re open to storytelling as is evident from the fact that they allowed eight days of front-page space and all these multimedia resources.

At first, we said, “let’s do a little solved clearance homicide story,” and this tale of a sympathetic young man occurred on our watch.

To begin with, my boss said “Empty your notebooks and tell me your story from beginning to end.”

Katia Bachko is on staff at The New Yorker.