SORRENTO — A 26-year-old man with an outstanding warrant for pulling a gun on his fiancée on Christmas Day chased down her car early Tuesday and fatally shot her in the mouth while the couple’s 10-month-old son sat in the back seat, Ascension Parish sheriff’s deputies said.

Shondrica Dejoie, who had just picked up her son from a visit with Jarvis McNair, his father, stopped her vehicle in the road on La. 22. McNair pulled onto the shoulder along side her vehicle under the Interstate 10 overpass in Sorrento, Chief Deputy Bobby Webre said Tuesday.

Sheriff’s investigators believe McNair then got out of his vehicle, walked around to Dejoie’s door and shot her shortly before 2 a.m., Webre said.

Woman fatally shot in Sorrento map _lowres

McNair then called 911 and waited for deputies to arrive.

“He was there when we got there,” Webre said.

Dejoie, 36, a New Orleans native who grew up in Gentilly but moved to Gonzales to be with McNair, died later Tuesday at an area hospital. Their son was not injured.

Dejoie and McNair had been dating for about three years, family member said.

The couple, who had an on-and-off relationship, had prior disputes that prompted law enforcement attention, including one in December in which McNair pulled out a gun which led to a warrant being issued for his arrest.

During an earlier incident in September, Dejoie told Gonzales police that she was “scared (to) death of McNair and is afraid that he may try to harm her,” according to a police report.

McNair was arrested and booked Tuesday on counts of second-degree murder, deputies said Tuesday.

Sometime before the shooting Tuesday, Webre said, Dejoie and McNair had met at a nearby grocery store to exchange their child.

The couple was trying to meet at a location closer to the house where McNair was staying with his mother in the Sorrento area, said Mondrica Davis, Dejoie’s sister.

Davis, 35, said the slaying was a “total shock” to her relatives, although her family in New Orleans knew of Dejoie and McNair’s problems to some extent. Davis added, though, that Dejoie was not one to share a lot of details.

“Everybody knew something was a little wrong with him, but we didn’t think it would go this far,” Davis said.

In December, a warrant was issued for McNair’s arrest after an argument turned violent Christmas morning.

Dejoie told police McNair pulled a gun on her after they got in an argument during which he pushed and hit her. She said McNair took their child and left the house with his mother.

Citing the ongoing investigation, Gonzales Police provided a three-sentence narrative of the December incident and would not release a more detailed report.

Though the warrant for McNair’s arrest was pending from the December incident on counts of domestic abuse and aggravated assault with a firearm, he had not been arrested on them until Tuesday, police said.

Sheriff’s deputies said they don’t yet know the motive for the shooting. Even before the December incident, McNair and Dejoie were involved in a dispute in September that prompted a response from Gonzales police, though no one was arrested.

Dejoie told Gonzales Police on Sept. 21 that McNair came in her home, started going through her purse and would not leave her alone. She added that there was nothing she could do about it, noting his name was on the mortgage.

In August 2014, Ascension land records say, Dejoie and McNair signed a mortgage for the home at 1942 S. Ringer Ave., Gonzales.

That’s when she told police she was “scared (to) death of McNair and is afraid that he may try to harm her,” though she said nothing “physical” happened during the argument at their home that day, a Gonzales Police report says.

“There’s no telling what he would do to her,” a police officer wrote Dejoie told him. “She just doesn’t trust him.”

At the time, the officer wrote that he told Dejoie she should consider getting a protective order, but there’s no evidence in the clerk of court’s filings that she ever got one, and no criminal charges were ever brought over the argument.

Deputies listed McNair’s home address Tuesday as South Ringer Avenue but the Gonzales police report from Sept. 21 indicates he was on his way out from the house the couple owned.

At the time of the Sept. 21 argument, Dejoie described McNair as her “ex-fiance.” That report and a follow-up report from later the same day indicate McNair was allowed to remove his belongings from the home.

Dejoie’s family members said he has been living more recently in Sorrento with his mother.

In one sign of the complicated nature of domestic disputes, Dejoie still referred to McNair in December as her boyfriend when she spoke to Gonzales police over their latest dispute. Webre also said that Dejoie, despite her troubles with McNair, was close to his mom, as was the couple’s young child.

The boy is staying with McNair’s mother in the aftermath of the slaying, Webre said. A woman who answered the phone Tuesday at the mother’s house declined comment.

Davis said her sister worked two jobs — one full-time at an express check business and one part-time at a restaurant.

Davis added that Dejoie had just met with her family Sunday to pick up her baby, whom her family had been watching while Dejoie worked.

Davis said her sister was a good person who would do “anything for anybody” and was the eldest sibling of two living brothers and two sisters.

“She was the one that kept the family together,” Davis said.

Follow David J. Mitchell on Twitter, @NewsieDave.