A Chicago man has been released from prison after serving more than 20 years of a life sentence he received for a fire that killed two people on the city's southwest side in 1993.

Adam Gray was released from an Illinois prison Wednesday after Cook County prosecutors recently decided to dismiss the charges against him. They said fire science advancements raised too many questions about his conviction.

Fire science advancements date to the early 1990s, but investigators didn't embrace the changes for years. Gray's attorneys spent recent years fighting his convictions based on the unreliability of the scientific testimony at his trial.

The fire occurred in March 1993, when Gray was 14. He says he's still having difficulty believing he's a free man after spending more than half his life in prison.