'Breonna Taylor is now attached to me for the rest of my life,' Sgt. Jon Mattingly says in exclusive interview

Taylor, 26, was shot by police in her Louisville, Kentucky, apartment in March.

In the seven months since he and his police colleagues executed a warrant at Breonna Taylor's apartment that resulted in her being killed in a hail of 32 bullets, Sgt. Jonathan Mattingly said on Tuesday that he's pondered what they could have done differently.

In an exclusive interview with ABC News and Louisville's Courier Journal, Mattingly, a 20-year veteran of the Louisville Metro Police Department, said one of the biggest things he would have done differently was to storm Taylor's residence without giving her time to answer what he claims were multiple knocks on her door accompanied by repeated announcements of "Police, search warrant!"

"We expected that Breonna was going to be there by herself. That's why we gave her so much time. And in my opinion that was a mistake," Mattingly, 47, told "Good Morning America" co-anchor Michael Strahan in a wide-ranging two-hour interview about the shooting that left him wounded, prompted nationwide protests, and led to demands that he and the other officers face homicide charges.

"What would I have done differently, the answer to that is simple now that I've been thinking about it," Mattingly said. "Number one, we would have either served the no-knock warrant or we would have done the normal thing we do, which is five to 10 seconds. To not give people time to formulate a plan, not give people time to get their senses so they have an idea of what they're doing. Because if that had happened ... Breonna Taylor would be alive, 100 percent."

Speaking publicly for the first time about the fatal encounter in which Taylor was shot six times, Mattingly expressed empathy for Taylor's family, saying the incident is something all good police officers dread.

"I feel for her. I hurt for her mother and for her sisters," said Mattingly, a father of four who recently became a grandfather. "It's not just a passing 'Oh, this is part of the job, we did it and move on.' It's not like that. I mean Breonna Taylor is now attached to me for the rest of my life. And that's not again, 'Woe is me.' That's me feeling for them. That's me having a heart and a soul, going as a parent, 'How do you move on?' I don't know. I don't want to experience it."

Mattingly, who was born and raised in Louisville as the son of a church pastor, said that on March 13 he worked a full shift before volunteering to assist other narcotics officers who had been investigating Taylor's ex-boyfriend, Jamarcus Glover, on allegations of drug trafficking.

He said that at a briefing attended by more than 50 officers, including police department command staff, Mattingly and the six other members of the team were told that Glover would be at another location on the list of warrants being simultaneously served across the city.

For more on the exclusive ABC News/Courier Journal interview with Sgt. Jon Mattingly, tune in to "Good Morning America" at 7 a.m. ET on ABC.

"They wanted to do the right thing and they said, 'Give her time to come to the door,'" Mattingly said.

He said that prior to arriving at Taylor's apartment, he and the others had no idea that Taylor's new boyfriend, Kenneth Walker, would be inside the apartment and armed with a licensed handgun.

Walker and 11 other witnesses at Taylor's apartment complex claimed they didn’t hear police announce themselves before they stormed through the door. Walker said he thought the police were intruders, causing him to fire a single shot that ignited a barrage of bullets.

Kentucky State Attorney General Daniel Cameron said that because Walker fired the first shot, Mattingly and Detective Myles Cosgrove were justified in their use of deadly force to protect themselves, which precluded prosecutors from pursuing homicide charges in Taylor's death.

Only one officer involved, Brett Hankison, who has since been fired from the police department, was indicted last month by a grand jury on wanton endangerment charges, for allegedly firing shots that penetrated a wall and entered a neighboring apartment occupied by a family. Hankison has pleaded not guilty to those charges.

Describing how the incident began, Mattingly said the team of seven officers arrived at Taylor's apartment after midnight and approached the front door in a line, "like a train."

He said that as the team reached the porch, a neighbor came out of his apartment and started arguing with them, engaging in an expletive-laced verbal dispute with Hankison.

"I remember him saying at one point, 'She's a good girl, leave her alone' or something to that effect," Mattingly recalled. "Finally, I looked at Brett and said, 'Leave that alone and pay attention to what we're doing.'"

Mattingly remembers initially banging on Taylor's door, but not announcing immediately that it was the police.

"So we get up, I remember banging on the door, it's open hand, hard smack, bam, bam, bam, bam. First time, didn't announce. Just hoping she would come to the door," Mattingly said.

He said the second time they banged on the door, they repeatedly yelled, 'Police, search warrant!"

Mattingly said they knocked on Taylor's door six different times. He said the last time they knocked, Detective Mike Nobles, who was standing on the opposite side of the door across from him, thought he heard someone coming to the door.

"So we stop, we listen. Nobody says anything. We yell again, 'Police, search warrant. Open the door if you're here,'" he said.

Mattingly said that when no one answered, Nobles rammed the door open. Mattingly said he was the first inside and while trying to clear a hallway he saw two figures side-by-side at the end of the hall.

He said the only light in the apartment was coming from a TV in a back bedroom and the lights on the guns of the officers behind him.

"As soon as I turned the corner, my eyes went straight to the barrel of this gun. I could see the tip of it. And my eyes just focused in on it as soon as I saw it," Mattingly said.

Saying that "everything happened in milliseconds," Mattingly said he heard a shot and immediately felt a burning sensation in his leg.

"As soon as I felt the smack on my leg and the heat, I -- boom, boom -- returned four return shots, four shots," he said, adding that he fired two additional rounds as the shooter rushed into a bedroom.

Mattingly said he fell to the ground and scooted to an area to seek cover. He said Cosgrove opened fire two to three seconds after he stopped shooting.

A ballistics analysis determined that Cosgrove fired the shot that killed Taylor, officials said.

"I reached down and felt my leg. I could feel a handful of blood and the heat -- I thought my femoral artery. I said I can't stand up because I'm going to pump the blood out if I keep pushing forward," Mattingly recalled. "I remember I scooted back and sat on my bottom and I scooted my gun out for some reason. I let go of it. Then I thought real quick, 'What am I doing? I can't let go of my gun.' I grabbed my gun and I pulled it back in and I yelled, I said, 'Man, I got shot in my femoral.'"

He said bullets were now whizzing over his head and he feared being shot again.

He said he mustered the strength to stand and hobbled out of the apartment, falling to the ground when his wounded leg gave out.

Mattingly said he was between two cars in the parking lot and could still hear gunfire.

"The shots from beginning to end, from my shot to Brett's last shot was maybe 10, 12 seconds," Mattingly said.

He said he didn't learn that Taylor had been killed until the next day when he got out of surgery.

"My first question was, 'Did she have a gun? Was she a shooter?' Because I didn't know what took place after I moved out," Mattingly said.

Asked by Strahan about how he felt when he heard Taylor was dead, Mattingly said, "It was tragic. It's horrible."

"Again, that's a situation that you dread, that you pray never happens," he said.

In the aftermath of Taylor's shooting, protests raged in Louisville for more than 100 days as Taylor's family demanded justice. They filed a wrongful death lawsuit against the city that was eventually settled for $12 million. As part of the settlement, the city admitted no wrongdoing in the incident, but it agreed to institute major police reforms.

Mattingly said the anger and violence that erupted during the protests could have been avoided had officials immediately released accurate information about what transpired at Taylor's home and had attorneys representing the family and Walker not fueled the fury with what he described as misinformation.

Mattingly, who is white, also said Taylor's death had nothing to do with her race.

"This is not relatable to George Floyd. This is nothing like that," Mattingly said of Taylor, who was Black. "It's not Ahmaud Arbery. It's nothing like it. These are two totally different types of incidences."

The veteran officer said Taylor's death was simply a matter of circumstances.

"It's not a race thing like people want to try to make it out to be. It's not. This is a point where we were doing our job, we gave too much time when we go in, I get shot, we returned fire," Mattingly said. "This is not us going, hunting somebody down. This is not kneeling on a neck. It's nothing like that."

Walker was initially charged with attempted murder of a police officer, but those charges were later dropped. Walker claimed in a lawsuit that Mattingly might have been shot by friendly fire from Hankison's gun.

Cameron, however, said that all of the officers who fired shots that night were armed with .40-caliber weapons. Mattingly was shot with a 9mm gun, which matched the one Walker fired.

When Strahan countered that Walker claimed he fired only a warning shot and pointed his gun at the ground, Mattingly scoffed.

"Let's get one thing straight, he wasn't shooting at the ground, he wasn't firing a warning shot. He was in a stretched out, two hands. It's called a Weaver stance, where your legs are apart. He's pushed out with two hands, looking straight at me. I saw his gun. Our postures were the same looking at each other when he fired that shot," Mattingly said.

When the grand jury decision came in on Sept. 23, clearing him and Cosgrove, Mattingly said he and his family watched it on television. He said that while he felt relieved, he knew he is still the subject of an internal probe by the police department, and that an FBI investigation looking into whether Taylor's civil rights were violated is still moving ahead.

He said his family members have also suffered greatly.

Mattingly said his family has received numerous death threats, including one just days ago in which someone threatened to kidnap his son, take him to a basement and torture him.

"When they started personally getting the death threats, as a father you can imagine how that would feel. When your daughters are getting threatened -- I mean, it just makes you feel helpless, number one, and angry at the same time because here you feel like you were trying to help the city," Mattingly said.

He said he is confident that he and the other officers involved did everything appropriately and that he feels betrayed by city officials, including Mayor Greg Fischer, for appearing to side with critics over cops.

"I spent 20 years giving my time, blood, my energy trying to help the city that I grew up in, that I love," Mattingly said. "And now when something tragic like this happens, now your family is the one that everybody wants to come after."

This report was featured in the Wednesday, Oct. 21, 2020, episode of “Start Here,” ABC News’ daily news podcast.

"Start Here" offers a straightforward look at the day's top stories in 20 minutes. Listen for free every weekday on Apple Podcasts, Google Podcasts, Spotify, the ABC News app or wherever you get your podcasts.