AMNA NAWAZ: Now an update to a story we brought you as part of our ongoing series Broken Justice.

In 2021, John Yang dug into the case of Lamar Johnson, a Missouri man serving life without parole for the 1994 murder of a man named Marcus Boyd.

GEOFF BENNETT: As John reported, Johnson always maintained his innocence, while two other men had confessed to the crime.

JOHN YANG: At Johnson's trial, his girlfriend said he left the house for less than five minutes to meet a friend, which turned out to be a drug deal.

Police testified he could have left and killed Boyd in no more than five minutes.

But look at a Google map showing the route between the two locations.

It takes about double that to go just one way.

And police said the other man on the porch identified Johnson, despite the fact that he said it was dark and that both attackers hid their faces.

LINDSAY RUNNELS, Attorney: They wore ski masks that had a cutout for the eye area and portions of the nose.

JOHN YANG: So, that's all that was visible?

LINDSAY RUNNELS: That's correct.

JOHN YANG: Just the eyes and a little bit of the nose?

LINDSAY RUNNELS: Right.

JOHN YANG: What's more, since Johnson's conviction, two men have confessed to being the ones who killed Boyd, and said Johnson had nothing to do with it.

KIMBERLY GARDNER, St. Louis Circuit Attorney: It shows that, sometimes, there is a miscarriage of justice.

JOHN YANG: Johnson says he remains hopeful that, one day, he will be free.

LAMAR JOHNSON, Serving Life Without Parole: From the beginning, I knew something was wrong because I got convicted for something I didn't do.

And so I knew the truth was out there somehow.

And I just didn't give up.

And knowing that kept me hopeful.

Like, as long as there's life, there's hope.

And so long, as there's hope, I know that the situation can be righted.

AMNA NAWAZ: Yesterday, after nearly 28 years behind bars, Lamar Johnson's murder conviction was overturned.

Johnson was given a new hearing, thanks to a change in Missouri law that allows prosecutors to reopen cases they believe were wrongfully decided.

And a judge ruled that there was -- quote -- "clear and convincing evidence that he was innocent."

GEOFF BENNETT: Following the ruling, the now 50-year-old Johnson walked out of a St. Louis courtroom as a free man to cheers.

The state attorney general who fought against his release said he would not pursue additional charges.