A ditch along Louisiana's I-10 near where the child was found.
CNN  — 

A truck driver found a 1-year-old alive in a ditch off an interstate highway in Louisiana this week, a day after the boy’s 4-year-old brother was found dead near the same freeway in what investigators think was a case of abandonment around the time tropical storm conditions hit the area, authorities said.

The boys’ mother, a Louisiana resident, has been arrested in Mississippi and faces murder and other charges, accused of abandoning the children in Louisiana, authorities said Thursday.

A Louisiana sheriff, who says he believes the 1-year-old spent two days along Interstate 10, including while Hurricane Beryl or its weaker iterations battered the western Gulf Coast region with rain and strong wind – is praising the truck driver for seeing the child and stopping to pick up him up Tuesday.

“We look at this 1-year-old as our miracle baby, (because) he was still alive,” Calcasieu Parish Sheriff Stitch Guillory said this week. “This kid spent two days out in the weather on the side of the highway. … Thank God that trucker (saw) him.”

An investigation began Monday afternoon, when the 4-year-old boy’s body was found floating in water behind a rest stop off I-10 in western Louisiana’s Calcasieu Parish, just across the Texas state line, the sheriff’s office said. No cause of death was immediately announced.

Aaliyah Jack

That day, Beryl made landfall in Texas as a hurricane and weakened to a tropical storm and tropical depression as it impacted Louisiana, dropping rain and delivering wind gusts of up to 60 mph to the parish, CNN meteorologists say.

Detectives eventually learned the 4-year-old had last been seen on Saturday with his mother, Aaliyah Jack, 25, of Lake Charles, and his 1-year-old brother, the sheriff’s office said. Police in Meridian, Mississippi, then found Jack without the 1-year-old, and she was arrested there initially on suspicion of failing to report a missing child, authorities said.

And on Tuesday morning, the 1-year-old turned up – alive – along I-10 back in Louisiana, authorities said.

‘That looks like a baby’

Truck driver Reginald Walton was driving on I-10 when he saw something “to the right, over in the … embankment,” he told CNN affiliate KADN, adding that he assumed it was a doll that someone had tossed out of a vehicle.

“But as I was passing by, I saw it move, and I say, ‘Hey, that looks like a baby,’” Walton, of Texas, told KADN.

Walton was traveling 60-75 mph, and it took him about a quarter of a mile to stop the truck, he said. He called 911, stopped the truck and ran back, he told KADN.

“Sure enough, there was a little boy sitting down the embankment there. As I approached him, he smiled at me, and then he stood up and started crying and walked toward me,” Walton said.

The 1-year-old was found near mile marker 10 – about 9 miles from the rest stop where his brother had been found dead the day before, the sheriff’s office said.

Deputies identified the boy as Jack’s 1-year-old son. He was taken to a hospital and later released to the state Department of Children and Family Services, Calcasieu Parish Sheriff’s Office spokesperson Kayla Vincent told CNN.

On Thursday, Jack – still in custody in Mississippi – was charged in Louisiana with second-degree murder, cruelty to a juvenile and two counts of failure to report a missing child, the sheriff’s department said.

It is unknown if she has an attorney.

Though Guillory said he believed the 1-year-old spent two days along I-10 – which would have included Monday, as Beryl swept through the area –?the sheriff’s office has not said whether investigators know precisely when the siblings were left.

Walton, meanwhile, told KADN he didn’t feel like he was a hero.

“I just feel it was God’s will for me to be in the right place at the right time,” he told KADN.

In this still from a video, truck driver Reginald Walton speaks to CNN affiliate KADN.

Grandmother: ‘I just want my grandbaby back’

Conswella Jack, Aaliyah Jack’s mother and a grandmother to the children, told CNN the last time she saw the kids was Saturday at her mother’s funeral, after which her daughter took them. Conswella Jack said she and her daughter had an agreement in which the grandmother would generally take care of the two boys, but Aaliyah Jack was free to see them whenever she wanted.

Conswella Jack learned of her 4-year-old grandson’s death on Tuesday after his paternal grandmother called to tell her, she said. Shortly after, a detective called her to confirm the death. She does not know what led up to the boy’s death or how her 1-year-old grandson ended up on the side of the road, she told CNN.

“I don’t know how anything like this occurred. … I know at this moment, I just want my grandbaby back,” the grandmother said.

Conswella was living in Houston when she heard the news, and has since relocated to Lake Charles, she said. She has been calling child protective services daily to receive updates on her surviving grandson, she said.

“I don’t know what to think. I buried my mother on Saturday, and now I learn this,” Conswella Jack said.

She described her 4-year-old grandson as “an awesome kid.”

“I’m sorry baby … that (you’re) gone. So sorry,” she said.

The grandmother said Thursday she still had not spoken with her daughter to learn what happened and hoped to reunite with her surviving grandson soon.

CNN’s Taylor Ward contributed to this report.