Chester Hollman spent 27 years and 11 months in prison; Terrance Lewis spent 21 years, five months, five days; and Johnny Berry spent approximately 24 years in prison. They have always maintained their innocence.

Together they spent nearly 74 years in prison for crimes they said they did not commit. In some cases, prosecutors or police knew the entire time that they were innocent and did nothing.

And, now, the court system agrees, overturning their convictions for second-degree murder, robbery and conspiracy. Correspondent Jericka Duncan talked to the three men, all of whom, now in their 40s, have been exonerated.

"Physically, I'm free," Hollman said. "But, like, it's just a lot of emotional things that I'm dealing with. I'm trying to find myself."

In July, a judge freed Hollman after prosecutors reopened his case and proved he was innocent of the 1993 murder for which he was serving life in prison. Authorities always had evidence that pointed to other suspects, but that evidence was not disclosed at the time of his conviction.

"Each day I've gotten stronger," he said. "I'm better."

Berry is marking the one-year anniversary of being home. "I'm still learning how to be free, to be honest with you," he said. "It's a learning process."

Lewis said, "Personally, I haven't been home not even 90 days. Although I've been happy, and I'm grateful, it's definitely been difficult. I have been enslaved, mentally as well as physically. I'm still traumatized. This fell upon us. They uprooted our life. When I say 'they,' meaning the system as a whole."

Philadelphia's district attorney, Larry Krasner, wants to correct those wrongs.

"The oath is to seek justice," Krasner said. "When somebody sits in a jail cell for a crime they did not commit, that is an injustice."

The former public defender assumed the top prosecutor job in 2018. One of his first missions was to beef up the Conviction Integrity Unit to investigate legitimate claims of wrongful convictions.

"There was a culture at various times of win at all cost," said Krasner. "And if that meant that you were gonna take the document that suggested there was a different suspect, a document that the Constitution requires you, as a prosecutor, to turn over to the defense, and you were gonna shred it, you did. And then there was a separate issue with certain detectives, and everybody who was in the system knew about it."

In his first week in office, he fired 31 employees.

"I did not enjoy it, but it was necessary to do," he said. "Especially as I see these exonerations happen, and guess whose names just keep coming up for having been involved in convictions of innocent people?"

"The people you let go?" asked Duncan.

"Yep. That story will be developing. Stay tuned."

In just 19 months, nine people have been exonerated.

Duncan asked, "What do you say about those ex-prosecutors who still believe that the people who've been exonerated are guilty?"

"I don't think this is the realm of belief; I think we should be working with facts. The system will always make mistakes, but the kind of prosecutor who is willing to do these things that are illegal and unconstitutional in order to have a win is the kind of prosecutor who's going to say to you, 'I still believe they're guilty,' because they're covering their own tracks."

The straight shooter also said he's determined not to waste court time, jail space or tax dollars on prosecuting low-level offenses, like marijuana possession or petty theft.

But when it comes to those issues, Krasner's critics said he's releasing criminals that are likely to commit another crime.

Duncan asked, "For judges who think or have said you've gone rogue and that you're a group of renegades, how do you respond to that?"

"Well, first of all, I have huge respect for the judiciary," Krasner said. "There's a small portion among them who I think take this personally when we say what we say – and we're very direct about it — that these policies and the people who were in the D.A.'s office caused mass incarceration."

As for the Conviction Integrity Unit, it's reviewed about 200 cases since Krasner took office.

"Conviction integrity is a particularly sticky situation because you are looking back on things that happened in the past," Krasner said. "And sometimes you're asking the same judge, who has already said no to overturning this conviction, to turn it over now based upon additional information."

Terrance Lewis said, "87 days ago, I was condemned to die in jail. That was my reality."

Johnny Berry said, "There are people still remaining behind the walls that are actually innocent. When you're innocent, and you run across another individual that's innocent …"

"Y'all souls connect," Lewis said.

"It's a connection," Berry said. "These are my brothers here. And I still got brothers that remain behind a wall. And that hurts."

But the men said they are not angry.

Krasner told CBS News the Conviction Integrity Unit actually rejects most of the cases it investigates.

So far, it's overturned convictions in about 4% of the cases it's looked into.