One man is using what he learned while in prison on a wrongful conviction to help exonerate others with a similar story.

Attorney Jarrett Adams was 17 when he was arrested and accused of sexually assaulting a University of Wisconsin student. He maintained his innocence from the start, but the attorney he was appointed by the court told him not to put on a defense, even though there was a witness who could corroborate Adams story. He was sentenced to 28 years in jail in 2000.

Adams told NBC Nightly News host Lester Holt that though he was locked up, he never gave up on fighting for his freedom. He spent a lot of time studying in the prisons law library.

Although I received my diploma from Loyola Law School in Chicago, I started law school in the Green Bay correctional facility, he told Holt.

He finally wrote a letter that caught the attention of the Wisconsin Innocence Project , a program that seeks to exonerate the innocent and reform the criminal justice system. Co-founder Keith Findley took up his case, but Adams already knew exactly what he needed during the appeal.

He had done his homework. He knew the case, factually better than anybody and he knew the law, Findley told Holt. He said, Look, the issue were going to win on is that ineffective assistance of counsel claim. Youve got to lead with that. Youve got to argue that.

Adams was finally exonerated in 2007. He went on to college, graduated from law school and began a clerkship at the same court that threw out his conviction. In 2016, The Innocence Project in New York hired him as a lawyer.

He recently went back to Wisconsin to represent Richard Beranek, who served time in the same prison as Adams. In June, Adams helped get Beraneks conviction overturned, winning his first case as a lawyer.

Adams told Holt that getting justice for those whove been wrongfully convicted couldnt make him prouder: Nothing pays me back more or my family more than me walking in the same court in the same state where they didnt even look at me when they gave me 28 years, but now they have to acknowledge me as attorney Adams.

Watch the full interview in the video above.