It’s been like a small bit of absolution . . . a second chance.

Fate brought State Police Lt. Stephen O’Reilly in just minutes too late to save Ally Zapp from a murderous sex offender in 2002.

But fate put him on the spot in time to save a 12-year-old girl named Alli this year. And today, the 31-year veteran cop, already named a “knight” of the American Police Hall of Fame, will be pinned with the state’s Medal of Valor.

O’Reilly, 55, led the charge through a barricaded door in New Bedford in January to save the young girl from the clutches of an accused double murderer.

Her name was Alli Barnes, the niece of a trooper O’Reilly works with, though he didn’t know that then. Gary Gomes is accused of holding her captive and stabbing her mother, Robyn Mendes, to death along with his own mother. He was allegedly waiting for another victim, Mendes’ ex, to arrive.

For O’Reilly, Alli’s innocent eyes flashed him back to the lifeless expression of Alexandra “Ally” Zapp, 30, whose killer Paul Leahy was washing her blood off his hands in a Route 24 Burger King restroom in 2002, when O’Reilly burst in after hearing screams.

“I always felt bad that I didn’t save (Zapp), that I didn’t walk in there five minutes earlier,” said O’Reilly, who battled post-traumatic stress disorder afterward.

“I couldn’t help but think, ‘Ally and Alli - one that you save and one that you don’t.’ It kind of brought a calmness over me that the Ally from Burger King was watching over the Alli in New Bedford. Whether it’s true or not, that’s the way I feel.”

He’s not alone.

“Steve O‘Reilly has become a dear friend since our daughter Alexandra’s murder seven years ago,” said Zapp’s mother, Andrea Casanova. “We knew that our Ally was so proud of his courage and his intense compassion for others.”

O’Reilly, who already wears the state’s Medal of Lifesaving and the Medal of Merit, said, “There’s a lot of crazy people out there. I enjoy putting them in jail.”