The man who told authorities he shot former New York Jets running back Joe McKnight has been charged with second-degree murder, the Jefferson Parish (Louisiana) District Attorney's office announced Thursday.

If convicted, Ronald Gasser, 55, will face life in prison without the possibility of parole, probation or suspension of sentence. As a result of the indictment, Gasser's bond was increased to $750,000.

According to legal experts, a key factor in the grand jury's decision likely was whether Gasser could have felt McKnight was attempting to break into his car during the December incident near New Orleans. According to a witness who spoke to Outside the Lines in the past week, McKnight did not appear to be acting aggressively toward Gasser just before he was shot three times outside of his car at an intersection after an extended road-rage confrontation.

The witness, Andrew Bailey, 26, told Outside the Lines that McKnight was standing in the small space between his Audi SUV and the passenger window of Gasser's Infiniti sedan, "talking with his hands" and appearing to be having a "general conversation." Bailey -- who was waiting to turn on the other side of the Terrytown, Louisiana, intersection -- said the 28-year-old former Southern California star was not trying to force his way into Gasser's car. "He never moved closer to the vehicle."

When police arrived, Gasser, 54, immediately admitted that he shot McKnight, who was unarmed, from inside his vehicle. Police took into custody and then freed Gasser, who is white, within hours, sparking backlash in the community and accusations of preferential racial treatment. Four days later, Gasser was booked into jail; police at that point said they did so after conducting more than 160 interviews and questioning the suspect for more than 12 hours.

Andrew Bailey was in his car across the intersection when Ronald Gasser shot Joe McKnight. Bailey's girlfriend, in the car with him, took this picture of Gasser standing over the body of McKnight, who was not yet dead. Courtesy Andrew Bailey

"Information provided from our sources indicates that McKnight exited his vehicle and attempted to enter through the passenger window of Mr. Gasser's vehicle while threatening him with serious bodily harm," attorneys Matthew Goetz and Gerard Archer, who represent Gasser, said in an email sent after-hours Thursday to The Associated Press.

They did not further describe the sources and Goetz did not immediately return a phone call to the AP on Friday.

The email added that while the attorneys don't yet have forensics evidence, they believe McKnight's wounds, and shell casings found in Gasser's car, will be consistent with the sources' account.

"Mr. Gasser did what he is legally entitled to do and defended himself. ... Mr. Gasser did not know Mr. McKnight nor was this in any way racially motivated. He feared for his safety and acted," said the email, sent by Goetz and signed by both lawyers.

"It is our understanding (which can be verified by a simple viewing of the photos of the scene following the incident) that Mr. McKnight drove his vehicle from several car lengths behind Mr. Gasser and then pulled over onto the shoulder of the road trapping Mr. Gasser's vehicle," the attorneys' email said.

After the shooting, Gasser "did what is expected of people who are following the law," they wrote. "He waited for the police and cooperated fully with the investigation."

In a news conference after Gasser's arrest, Jefferson Parish Sheriff Newell Normand criticized comments on social media, declared that the incident wasn't racially motivated and noted that a witness who said Gasser stood over McKnight and shot him was discredited by the coroner's report. "Two people engaged in bad behavior that day," he said. "Why? I don't know."

While the results of the autopsy indicated that Gasser did not shoot McKnight while he was lying on his back, Bailey, along with another witness who spoke to TMZ, said the shooter did stand over McKnight as he died, gun in hand.

"There were people running over to check on Joe ... he was swinging the gun at everybody," said Bailey, who gave his full account to police. He instructed his girlfriend, who was sitting in the passenger seat, to take a photograph of Gasser standing over McKnight's body.

One of the bystanders who rushed to the scene was Wendell Sam, a Navy officer. According to Normand, Sam -- who happens to be a relative of Bailey's -- urged Gasser to put his weapon down, explaining that he "did not want to shoot a military officer," then tried to administer CPR to McKnight after pulling his body from between the cars. A video of the lifesaving attempt was posted online.

A zoomed-in version of Bailey's girlfriend's photo. Courtesy Andrew Bailey

Ken Levy, an associate law professor at LSU, said the defendant's attorneys might argue that Gasser's actions were justified under Louisiana Revised Statute 14:20, which says a person can use deadly force to thwart someone from unlawfully entering their car. "You have to reasonably believe that they're trying to get in, and they present a threat of serious bodily injury or death," Levy said.

While Louisiana's justifiable homicide statute also has a so-called "stand your ground" provision, which states that a person is not obligated to retreat in the face of a threat, Levy said the law might not factor into Gasser's case. The provision was notably invoked in the trial of Cardell Hayes, who shot and killed former NFL player Will Smith in New Orleans last year. "That would be relevant if McKnight had challenged him to a fight, and [Gasser] had gotten out of the car," he said.

Gasser's lawyer, Gerald Archer, did not respond immediately to a request for comment.

McKnight, one of the most highly touted football recruits in the country when he graduated from John Curtis Christian High School in River Ridge, Louisiana, played at USC and then for the Jets for three years. After a stint with the Kansas City Chiefs in 2014, he last played for the CFL's Saskatchewan Roughriders.

Speaking briefly to Outside the Lines, Johanna McKnight, Joe's sister, said, "We very much hope for justice."

Mina Kimes is a senior writer for ESPN. She can be reached at Mina.Kimes@espn.com. Follow her on Twitter at @minakimes. Information from The Associated Press contributed to this report.