Hi, I'm Dan Sleppian, investigative producer for Dateline, and you're about to hear a clip from the second episode of my new podcast, Letters From Singsing.

It's a story about a man convicted of murder, his fight for justice, and how the letters he sent me sparked a 20-year investigation that changed both of our lives, and the lives of so many others.

To hear this and more episodes, search for letters from Singsing wherever you're listening, and make sure to follow the podcast.

Listen, family, pictures, school, papers that I've kept. He always got very good grades. This is excellent. He loved dinosaurs. He did a dinosaur project.

And you could see that he was such a happy person, always with the smiles and the laughter and friends. He had a lot of friends.

I'm with Maria Velasquez, JJ's mother. She's showing me his childhood drawings, old report cards, photos of JJ when he was a kid.

I used to feel like a taxi driver running them to the movies, running them to shows, running them all over the place, because he always, oh, my mom will take you, my mom will take you.

And I wind up like with five or six boys in my car driving them to the movies, taking them bowling, doing all kinds of things, you know.

This is one of my favorite.

Maria lives in Havestra, a town in New York on the Hudson River, directly across the water is Singsing, the maximum security prison where her son is locked up.

Maria pulls out another set of photos. These look more recent in them, JJ's older.

When we go to the FRQP's, the family reunion project, we always take pictures.

The program that Maria is describing lets incarcerated people with good behavior, visit with their families for a couple of nights in a trail or on prison grounds.

We've celebrated birthdays, my birthday, his birthday, Mother's Day, Father's Day, all on FRPs.

She tells me that she always tries to spend the major holidays, like Thanksgiving and Christmas, with her son.

There's no gifts, there's no tree, you know what we're used to.

But I've gone outdoors and picked a little bush, come inside and put little things on it and made a tree out of it.

And we've always managed to just keep the family going no matter what.

But my reason for coming to see Maria went beyond just hearing stories about JJ's past.

He insisted he had proof he didn't murder Al Ward, the retired police officer.

He told me that he had an alibi.

I have always felt so grateful to have known where my son was when they said that he was someplace else.

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