The victim of a 2012 carjacking in Algiers Point took the witness stand Wednesday in Criminal District Court to describe how her neighbor, Harry “Mike” Ainsworth, leaped onto her car hood and bashed the windshield with his arms and fists, trying to halt the crime before he was fatally shot through the windshield in a killing that stunned the normally sedate neighborhood and the entire city.

The halting testimony of schoolteacher Anita Hedgepeth came on the first day of the murder trial of Kendall Harrison, who was 17 when Ainsworth was shot dead in front of his two young sons about 7 a.m. in the 500 block of Vallette Street.

Hailed as a Good Samaritan, Ainsworth was a 44-year-old contractor who had volunteered for various police causes and was a member of a booster group for the Police Department’s 8th District before he collapsed onto Hedgepeth’s front lawn.

He had just dropped his boys, ages 9 and 10, at a bus stop on the morning of Jan. 25, 2012. The boys witnessed the shooting and knelt stunned over his body, later screaming in what Hedgepeth called “the worst sound I’ve ever heard in my life.”

Moments earlier, Hedgepeth said, she saw a man round the corner. She looked away, then heard a tap at the window of her Saturn Ion. He asked if she knew what time it was. She turned to the clock, then turned back to find a gun pointed at her head.

“Gimme the (expletive) car,” he ordered through the rolled-down window. She said she wasn’t sure how she got out of the car, but the man got inside, and within seconds Ainsworth was atop the hood.

“I backed up toward the rear of the car, just still screaming, then I heard three shots fired. Mr. Ainsworth said, ‘He shot me.’ And I believe he said, ‘Run,’ ” she said.

Asked how she felt about his actions, she paused, then said, “I don’t know how to describe how I feel about that.”

Hedgepeth couldn’t identify Harrison in a photo lineup. “I had only seen his face for a few seconds, and behind a gun,” she said.

But a “touch” DNA test from the Saturn’s steering wheel turned up a match to Harrison, according to Assistant District Attorney Payal Patel. Tips from the community also pointed toward Harrison, prosecutors said, leading to his arrest about a month after the killing.

Patel called it “a very important case to this city,” telling a jury that the killing sparked an intensive investigation that included New Orleans police, the FBI and other agencies.

She said a witness followed the shooter up the street while on the phone with a police dispatcher, but that the shooter ran away.

A cousin of Harrison’s, who was at a house up the street, will take the stand to say that Harrison was there at the time of the shooting, Patel told the jury. His testimony, she said, will contradict a statement Harrison gave to police, saying he hadn’t been in Algiers Point for a few weeks before the crime, she said.

Harrison never confessed to the shooting, and no gun was recovered.

During his opening statement Wednesday, Harrison’s attorney, Lionel “Lon” Burns, launched into an animated, often racially charged attack on police, prosecutors and even Ainsworth.

Burns, a former prosecutor who launched a run against District Attorney Leon Cannizzaro this year before the Louisiana Supreme Court disqualified him for failing to file tax returns, suggested that Ainsworth provoked his own death in an overzealous bid for vigilante justice.

“He’s all copped up. He had on a cop shirt and a cop hat. Unfortunately, he’s all about being a neighborhood policeman,” Burns said.

“If I were in that position, I would have used my big booming voice, said, ‘Hey, get out of that lady’s car. Leave that lady alone.’ I’m not going to run over, jump on the hood of the car, kick the windshield out of the car, unless maybe I’m just in the zone,” he said.

Burns was aiming to exploit the fact that autopsy reports showed Ainsworth’s body tested positive for the chemicals found in marijuana.

“Let me come down off my trip. Let me come down and land the plane, come down to reality and realize I’m not a cop. I’m not a superhero,” Burns said to the jury.

He also accused police of conducting a weak investigation and accused Cannizzaro’s office of enlisting Harrison in what he described as the “Boys to Men” program.

“Take young men who are poor, charge them with the most horrific crimes, let them languish in prison for two to three years and maybe they’ll get a plea deal. Maybe they’ll just say, ‘OK, OK, I did it,’ ” Burns said.

“Send him to Angola. Nobody’s going to miss him. The detective didn’t do enough work? Send him to Angola. We got some neat black DNA? Send him to Angola. Because we said he killed that white man.”

Harrison, now 20, faces murder and armed robbery counts. If convicted, he faces a life prison sentence.

The trial will continue Thursday.

Follow John Simerman on Twitter, @johnsimerman.