Jharrel Jerome is no stranger to emotionally complex and potentially draining work, after appearing in “Moonlight” and co-starring in Audience Network’s “Mr. Mercedes.” But his latest role, as Korey Wise, one of the young men falsely convicted of a brutal attack, in “When They See Us,” Ava DuVernay’s limited series about the Central Park Five, challenged him like no other. Jerome plays Wise both at age 16 at the time of his arrest, and in his late 20s after serving 12 years in jail.

You’re the only actor in “When They See Us” that plays both ages of the character, how did that come about?

It was late 2017 when I saw on Ava’s Instagram that she posted about the Central Park Five and said she couldn’t wait to tell this story, and I actually DMed her — I didn’t know her at the time — but I just said, “This is going to be so incredible.” I didn’t get a response; she’s a little busy! Months go by and my team mentions she’s casting it, and all I knew was I wanted to be a part of it, however it was — if I had to be a friend, if I had to be the man that did it, I wanted to be a part of this story. Being from The Bronx — being from right around the way — and being Dominican, a person of color, it was just so important to me from the moment I saw it. These men are here and alive and if I did this I would be doing something way bigger than me and my passion for acting. I put myself on tape, but the problem was I had all of this facial hair, and when I have all of this hair people think I’m 25 or 26, and when I don’t have it, people think I’m 14 or 15. I’m actually dead in the middle; I’m 21, so it’s weird. But I taped myself with the hair, and we got word back from the team saying, “We love it, but can he shave his face? We would love to see him for Young Korey.” And the production I was working on at the time didn’t let me. So for months I was calling back to ask if they cast the role, and lo and behold, June comes, I wrap my show, fly to New York, shave — got my baby face on — and I got to meet with Ava. I read it and she looks at me and she goes, “I’m going to give you the older Korey sides.” I was like, “Whoa, I just shaved my face to play the younger part, and now you want me for the older?” But no matter what, when Ava hands you something, you do it; it’s an opportunity and you make it happen. So she gave me the monologue from Part 4 and I went downstairs to look it over, found some beats with the knowledge of who Korey was, and I went back up and did it, and two days later she personally called my cell phone when I was about to go to bed, and she said, “I would love to offer you the role of Korey Wise, but here’s the trick: I’m casting a young and older person.” So I was thinking, “OK who’s going to be my older person?” And she said, “I would love for you to play both. I would love for you to work a little harder to play both.”

How did you find who Young Korey was?

It’s funny but I found his young side by talking to him today; he’s in his young mode, listening to all your favorite ’90s rappers, matching his hat to his Jordans; he’s all about that youth and freedom of life and feeling that. So I took that and ran with it. We don’t have any footage of how he really was talking to his friends, talking to his girlfriend before the incident, but I can picture him being smooth and cool and suave, and so I tried to give him that feel. He is a real New Yorker — all of them are; they’re real Harlem men and they’re so proud of it, so I also incorporated that pride into the part. And I brought my voice up to a little higher pitch because I knew if I did that I’d have room to bring it down for the later [episodes] when life of jail on you has affected you. Imagine being in solitary for four or five years and not speaking to anybody except for a guard who comes once a day? You start to lose your communication skills and all that. So it was about the mental process. I think when he was young he had a lot more going on in his head in terms of, “Got to be cool, got to get Lisa, got to stay me” — until everything snaps and you start to see his mind deteriorate, and so for me, it was finding those darker places as we went along.

How much time did you have in between shooting the Young Korey parts and the older Korey parts in order to physically transform?

While they were shooting Episode 3, which Korey doesn’t appear in at all, that was three and a half weeks of training that I did. I didn’t get massive, but you can see it: I gained eight pounds of muscle and my shoulders got broader. I definitely did a lot of pushups before shooting. I was doing six days a week, twice a day. I was eating 3500 calories a day. Food is nice, until you have to really eat after you’re full! I had a physician and trainers and people giving me advice. For me in my regular life, I do not work out; I love McDonald’s; I love fast food, and so it definitely was a huge challenge to get into that mindset, but all I thought was, “If Korey can spend 12 years in jail and come out the man he is, I can do three weeks in a gym.”

How did actually getting to know Korey affect how you portrayed him?

Before I knew Korey I was extremely nervous. I’m playing a real person and this is real life. I have a lot of responsibility and I want to do justice by Korey, and that pressure I felt until I met him. When I met him, he took his chain off of his neck and put it around mine and said, “You’re Korey now.” And he had a lot of confidence in me. It became about, “I’m doing this for my brother, somebody I’m inspired by.”

Did he also help you with understanding what he went through in jail?

I never once spoke to Korey about his experience in jail; I never talked to him about what he went through. Ava gave that to me in the script, and Ava learned that through her research. I did ask him if he had friends in jail, and he gave me a couple of stories of some of his friends, but you can already feel that weight when you hear a story like this. So when I was sitting in the jail with real bars — we were in real jails with real inmates down in the next corridor — it’s not hard to dive into that mindset.

Why do you feel it was important to tell this story narratively, in addition to the documentary that was already available?

The show gives you the heart and the family life and the realness. They’ve heard about us through the grapevine, they kind of know what they went through, but instead of just hearing, “Korey spent 12 years in jail,” you see Korey inside of jail — and instead of hearing “the cops manipulated five young boys of color,” you’re inside the holding cell and you see the cop walk in and see why he was doing it, what his mindset was, and you hear his words. It’s opening the actual book and reading about it and their emotions and their thoughts and everything you see in the show is from their words — their mouths; Ava didn’t create a new part or a new idea, she kept it all in the lives of these men and kept it as real as possible. She made saw they approved before we moved on; she cares. So you’ll actually see them this time; it’s why it’s called “When They See Us.”

How do you feel most personally changed by your experience with this show?

Besides a little muscle, the show taught me what it’s like to fear and what it’s like to be cautious, but it also taught me what it’s like to overcome and what it’s like to feel pride. I grew up family-oriented, surrounded by love — I didn’t grow up getting bullied; I didn’t feel the pain. I got to learn the pain by doing this project, and I think learning pain — and heartbreak — teaches you a whole lot. As a man, as a person, as an artist who’s a young, black man, it taught me to keep my chin up and how to run that extra mile and work as hard as you frickin’ can. And I’m also walking around looking at young black men in the street, strangers I don’t know but who are my brothers, and I look at them and I’m like, “I hope you’re safe, I hope you’re OK.” Of course I knew before I did this project what it is like, growing up in the Bronx [but] doing the show put everything into a deeper perspective for me.