CHICAGO (CBS) — Mario Casciaro was surrounded by his relatives as he left Menard State Prison on Wednesday, his murder conviction overturned by a state Appellate Court judge.

On Thursday, he reflected on his judicial odyssey.

“I am not an angry person,” he told CBS 2’s Mike Parker. “I just want to prevent this from happening to the next person.”

Casciaro was charged with the 2002 murder of 17-year-old Brian Carrick over an unpaid drug debt.

It allegedly happened in the stock room of a Johnsburg supermarket.

Carrick’s body was never found.

It took prosecutors three trials to find a jury that would vote guilty.

But later, the key witness recanted his testimony and said he lied under oath.

The Appellate Court ruled that “the state’s evidence was so unreasonable, improbable and unsatisfactory that a reasonable doubt exists.”

Casciaro’s goal is to become a lawyer and get into politics.

He wants prosecutors to be held accountable for cases like his.

“A prosecutor can frame somebody that he just happens not to like. There’s no problem with it. Not a slap on the wrist, he just moves on to the next guy.”

He still wonders what really became of his friend, Brian Carrick.

“All the time, it’s one of those questions that you’re saving to ask God, other than what’s the meaning of life.”

One day, he hopes to talk with Brian’s family.

“It’s sad,” he says. “They’re good people.”

The McHenry County’s state’s attorney office had no comment on Casciaro’s blast at the prosecutors.