A Philadelphia man sentenced to life in prison in 2007 for killing his friend is now free. Dontia Patterson was exonerated and released Wednesday following an extraordinary court motion from Philadelphia's district attorney who asserted the conviction was "an egregious example of police and prosecutorial misconduct."

Dontia Patterson CBS News

The case is stirring up controversy between the city's new district attorney and the former prosecutor who secured Patterson's conviction. The 29-year-old, who had been on house arrest since March after his conviction was vacated, has always insisted on his innocence.

One of the first things Patterson did was pick up his 11-year-old daughter at her bus stop.

"You've seen her grow up without being with her. What kind of pain did that bring to you?" CBS News' Michelle Miller asked Patterson.

"A lot. A lot of days I cried," he replied.

A judge dropped all charges against Patterson at the request of newly installed District Attorney Larry Krasner.

"We were able to show the prosecutor, in this matter….There was a lot of evidence that they had not considered or seen," said Patterson's attorney Hayes Hunt.

Richard Sax CBS News

Patterson was arrested in 2007 for the murder of his friend, Antwine Jackson. His first trial in 2008 ended in a hung jury; he was convicted at a retrial in 2009. The DA claimed this week that "although Patterson was tried twice, neither jury heard the truth" adding "the prosecution and police did not turn over strong evidence in their possession that identified the likely perpetrator."

The motion says another unnamed suspect was "murdered just a few months after Jackson's murder."

Retired prosecutor Richard Sax handled Patterson's second trial. He maintains that Patterson is Jackson's killer.

"I resent that they said I withheld evidence because I did not, and never have, and never been shown to or established by any court that I have. So that's nonsense," Sax said.

Marissa Bluestein is the executive director of the Pennsylvania Innocence Project, which has been working on Patterson's case for the last four years.

"That prosecutor has always seen this case through the lens of Dontia Patterson is guilty. And he is caught up in that narrative and that narrative is very tight to him," Bluestein said.

Patterson said he's taking it "day-by-day, step-by-step." And those 11 years lost?

"You know, just gotta stay strong," he said.

This is the latest Philadelphia case where someone who spent years behind bars has been cleared.

Rapper Meek Mill was freed last month. DA Larry Krasner campaigned as a reformer who described the city's district attorney's office as hell-bent on winning cases at any cost.