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Napanoch, New York (CNN) -- Inside the fortress-like walls of the Eastern New York Correctional Facility, Richard DiGuglielmo Jr. is plagued by a question that has haunted him for more than 15 years: "What would you do if someone were swinging a baseball bat at your father's head?"
The choice he made on a crisp autumn day not only changed his life, it cast doubt on an entire justice system in Westchester County, New York.
That's because after serving 11 years in prison for the murder of 37-year-old Charles Campbell, DiGuglielmo was released on appeal after a judge ruled the former NYPD officer was charged inappropriately and evidence withheld by local prosecutors would likely have changed the jury's guilty verdict.
"It was surreal," says DiGuglielmo describing the day in 2008 when his conviction was vacated and he was allowed to leave prison a free man. "The first thing I did was get out of the car and look around and make sure it was real -- that my hands weren't shackled together, my ankles weren't shackled and I was like, wow this is real."
DiGuglielmo immediately found a job and an apartment. During a night out with friends who had stuck by him, Richie -- as his friends called him -- met the love of his life, who would soon become his wife. For the next year-and-a-half, DiGuglielmo led an idyllic life.
It all ended in 2010 with a stunning twist of fate. New York state's highest court overturned the lower court and said new evidence would not have influenced the jury.
The four-judge panel sent DiGuglielmo back to prison to finish his 20-years-to-life sentence.
Richie DiGuglielmo stands about 5 feet 10 inches tall with a solid, muscular build and firm handshake. He wears a drab green prison uniform, his shirt neatly tucked into his pants.
Not a day goes by that he doesn't relive the day when everything changed.
That day was October 3, 1996, in the village of Dobbs Ferry, just 30 minutes outside New York.
DiGuglielmo had finished working his NYPD shift as a transit officer in the South Bronx. His father, Rich Sr. -- age 54 -- was recovering from a heart attack, so Richie stopped by the family deli to help his dad and brother-in-law, Robert Errico, with the pre-dinner rush.
Before long, a brand new black Corvette driven by sanitation worker Charles Campbell pulled into the building's reserved parking lot. Campbell chose one of the lot's few empty spaces, despite a sign saying "Parking for patrons only."
Campbell, an amateur boxer who also worked part-time with underprivileged kids, had just come from a workout and was picking up some pizza across the street. His brother, the Rev. William Campbell, describes "Chazz" as "a wonderful athlete, wonderful person. He was a Christian. He loved kids, loved people, all people."
Parking was a major problem along the perpetually busy road. The deli served almost 600 customers a day and, with customers driving in for other businesses in the two-story building, oftentimes there was nowhere to park. DiGuglielmo's father says several of those businesses had started to withhold rent demanding the problem be fixed in response to customer complaints.
Charles Campbell knew nothing about the rent issue when DiGuglielmo Sr. asked him to move his car to another parking lot, not far away. Campbell refused and went to buy the pizza. So the Deli owner did what local police had advised him to do, post a "no parking" sticker on the window of Campbell's Corvette.
When Campbell saw what was happening he raced across the busy street. Rich Jr. says he stepped between Campbell and his father, hands raised, trying to calm Campbell. That's when Rich Jr. says Campbell threw the first punch, "It was like getting hit by a hammer. They were hammer blows. He just was outta control. He was someone who didn't want to listen to reason or anything like that at the time."
According to the DiGuglielmos, it took all three family members to subdue the athletic Campbell, who finally threw up his hands and said, "That's it. I've had enough!"
At that point, Rich Jr., went into the deli, he says. Campbell then walked over to his car and Rich Sr. followed him to hand him his cell phone and a sweatshirt that had come off during the fight.
But instead of getting in the Corvette and driving away, Campbell went to the trunk and pulled out a metal baseball bat.
He struck the elder DiGuglielmo twice, shattering his kneecap and then cracking his wrist.
From inside the deli, Rich Jr. saw Campbell swinging the bat at his father, so he reached under the cash register and grabbed a gun. Rich Jr. says, "From the time that bat came out to the time it was over, it was a matter of four seconds, five seconds. My training just kicked in."
Rich Jr. ran outside and fired three times, hitting Charles Campbell squarely in the chest.
It was the first time DiGuglielmo had shot anyone, much less taken a life.
And yet, because he believed his father's life was in danger from what he perceived as a "deadly weapon," the swinging bat aimed at his dad's head, DiGuglielmo was certain he would be cleared quickly and be able to return to work.
Instead, all three family members -- the father, son and brother-in-law -- were charged with assault.
Rich Jr. received the most serious charges, two counts of murder: intentional murder and murder with depraved indifference.
At a news conference, then-District Attorney Jeanine Pirro said a witness -- who she didn't name -- reported hearing racial slurs during the incident, triggering a year of racially charged demonstrations and protests outside the DiGuglielmo deli. But during the trial, no witnesses ever testified about hearing racial slurs.
Two witnesses who were closest to the incident, Kevin O'Donnell and Michael Dillon, initially said DiGuglielmo was defending his father.
But by the trial date, after repeated questioning by Dobbs Ferry police, O'Donnell and Dillon had changed their stories to say that DiGuglielmo did not appear to be acting in defense of Rich Sr.
Prosecutors said the DiGuglielmos ganged up on Campbell so he had no choice but to defend himself with the baseball bat. In her opening statement, Assistant District Attorney Patricia Murphy told jurors, "This is a case about revenge. This is a case about retribution. This is a case about payback. This is a case, ladies and gentlemen, about rage."
'Alright y'all, back on up'
Although Campbell's brother William -- who is a Christian minister -- wasn't there that night, he says he knows his brother wouldn't have grabbed the bat unless he was provoked.
"I know Chazz," says William Campbell. "When he got that bat, the idea of getting that bat was to just show, 'Alright y'all, back on up. I'm not trying to start something here, but I will finish it.' It was something to show them, 'Hey, this is getting serious. We better cool it down.' It didn't happen that way. They kept charging so he swung once at the father."
Although the fight began over a parking space, the DiGuglielmo's say that's not why it ended as it did.
"If there weren't a baseball bat, there would never have been a gun," says Rich Sr.
All three family defendants were found not guilty of assault over the fight with Charles Campbell.
However, prosecutors successfully convinced the jury that Campbell was backing away while the bat was in midair. Though they'd called the shooting a case of "revenge" and "payback," DiGuglielmo was acquitted of intentional murder and instead convicted of murder with depraved indifference.
He was sentenced to 20 years to life in prison.
What the jury never heard, however, was that key witnesses O'Donnell and Dillon had changed their stories after repeated interviews and questioning by police. Originally, witnesses told police Rich Jr. was defending his father.
At trial, the story changed to support the prosecutor's contention that Campbell was backing away.
The Dobbs Ferry Police Department, and the Westchester County District Attorney's office denied CNN's requests for interviews.
After initially refusing CNN's interview requests, former District Attorney Pirro -- who now hosts a TV talk show -- responded with a written statement.
In it, Pirro failed to answer CNN's questions, such as: if Pirro felt the issue of race was a motivation for the incident why didn't race surface at the trial? Why were original witness statements withheld?
The statement reads, "Richard DiGuglielmo's guilt has repeatedly been affirmed by three appellate courts (Appellate Division twice and the Court of Appeals) in the 15 years since an innocent, unarmed man was senselessly shot and killed by DiGuglielmo in a dispute over a parking space. The defendant received a fair and impartial jury trial led by a team of career prosecutors who continued to vigorously defend that conviction even after my administration. Since that time the defendant's claims have repeatedly been held to be without merit. My thoughts and prayers continue to be with the family of the man gunned down in the prime of his life, Charles Campbell, and who are forced to relive this tragedy while they mourn his loss."
The DiGuglielmos hired a private investigator to look into Rich Jr.'s case. The investigator unearthed two witnesses who said they had changed their stories because of police pressure.
The family appealed based on this new evidence and Westchester County Court Judge Rory Bellantoni got the case. Bellantoni took two years to comb through materials from the original trial. He then held a hearing to determine if witnesses were coerced and if they then changed their statements due to that pressure.
Bellantoni blasted prosecutors in a 69-page ruling that said they had a "win at all costs" mindset and their case was a "wholesale assault" on the justice system. Had the jury heard that witnesses changed their statements, Bellantoni said the verdict very likely would have been different.
On September 28, 2008, he vacated Rich DiGuglielmo's conviction and set him free.
However, the New York Supreme Court had the last word. Eighteen months after Rich DiGuglielmo Jr. was released, a four-judge panel ruled that even with new evidence it was not clear a jury would have found DiGuglielmo not guilty of depraved indifference murder.
Bellantoni says he firmly believes this reversal was a major miscarriage of justice.
"I don't know how they can say that," says Bellantoni. "If 12 people heard that he stuck by his story and finally changed it because he just didn't want to be harassed by the police department any longer, might the verdict have been different? The answer for me was yes."
On June 3, 2010, Rich DiGuglielmo Jr. surrendered himself to the courts and is finishing his sentence.
DiGuglielmo isn't eligible for parole until 2019 and continues to fight an all-consuming uphill legal battle.
"It's been a tragedy from day one and I won't belittle that in any way, but I don't know," he said. "How does a judge send you home and then another judge say, 'Oh no, well we don't agree with you so we're going to send you back.' "
Although not a day goes by that DiGuglielmo doesn't think about Charles Campbell, his father's self-imposed prison may be worse than the physical one where Richie resides.
That fateful day of the shooting clearly haunts DiGuglielmo Sr., "I would wish my son was never there. Whether I got killed or not, it doesn't make a difference to me. What do I have now? Yeah I have my wife and my daughter. But my family's torn apart. Literally torn apart. Where's my son? It rips my guts out to go up to see him. It never should have happened."