New Orleans police said Wednesday that they have reconstructed a six-car pileup that happened last month on Interstate 10 — an unusual crash in which a young boy and his mother lay dead yet unnoticed on the side of the highway for two days — and that criminal charges appear unlikely in the case.

“The investigation is ongoing, but based on information that detectives have developed at this point, we don’t believe there was criminal intent on the part of the driver who we believe hit the individuals,” said Tyler Gamble, a Police Department spokesman.

The results of the investigation will be forwarded to the District Attorney’s Office, Gamble said, but the fatalities appear at this point to be “an unfortunate accident.”

Based on a reconstruction of the Sept. 20 crash and a paint chip found during an autopsy of the boy, police believe 4-year-old Richard Gorden III and his mother, Tracy Jefferson, had climbed out of their Chevrolet Impala after an initial collision on the interstate and had been standing in the highway’s westbound lanes when an F-150 pickup crashed into their empty vehicle and also struck them.

A recent search warrant, filed in Orleans Parish Criminal District Court, described the paint chip as being “consistent with the color” of the damaged F-150 involved — a pickup driven by a Mississippi woman who has insisted she never laid eyes on the victims.

The lead investigator in the case, Detective Kevin Thompson, wrote in the warrant that the mother and boy appeared to have been “thrown over the concrete guardrail of the interstate and landed in knee-high grass where their bodies remained” for more than 48 hours.

Gorden’s grandfather, Richard Gorden Sr., said he was unsatisfied and “highly upset” at the Police Department’s findings, adding he believed detectives had “bungled” the crash investigation.

“Two people are dead,” Gorden said late Wednesday. “If two people are dead, isn’t someone negligent?”

Magistrate Judge Harry Cantrell gave investigators approval late last month to obtain a paint sample from the F-150, which remains in police custody, and to compare it with the evidence discovered during Gorden’s autopsy.

The paint analysis would have required the hiring of an outside contractor but hasn’t yet been conducted, Gamble said, in part because it “just wasn’t necessary, especially given at this point that detectives don’t believe that any charges should be filed.”

He added that the F-150 was the only vehicle of its kind at the scene, and that the paint chip recovered from the boy’s autopsy appeared to have come off the vehicle.

The driver of the F-150, Michelle Lulei, 33, of Tupelo, Mississippi, declined to comment Wednesday.

The crash happened shortly before 4 a.m. on a Saturday morning in the westbound lanes of Interstate 10 near the Louisa Street exit, at the bottom of the Industrial Canal high-rise bridge.

Bernard Meggs, who was driving a Chevrolet van, said the pileup began when he was rear-ended trying to avoid an object in the road that he said appeared to be a ladder.

“We slowed down, but the guy behind us didn’t slow down,” Meggs said earlier this month. “He must have been going about 100 mph, and he ran into the back of me and my son.”

Vehicles began piling up behind Meggs, who said he felt lucky to make it out alive. Shortly after the initial collisions, Jefferson, having swerved to avoid the pileup, appears to have veered into the right lane guard rail in her Impala and caromed off it. Meggs said her vehicle appeared to be headed straight toward him and his son as they sat on the median.

In an interview earlier this month, Lulei, the driver of the F-150, said she had been driving down the high-rise in the left lane and “saw the (first) four cars hitting each other.”

“I quickly saw a car parked horizontally in the middle lane, and I thought I could swerve and miss it, and I didn’t,” she said.

Lulei said she struck Jefferson’s vehicle broadside in the middle lane, where it had spun around and come to a rest perpendicular to traffic after hitting the right guardrail. But she insisted no one appeared to be in the darkened Impala, and that she never saw Jefferson or her son on the interstate. She said she assumed the driver might have been intoxicated and abandoned the car on the roadway.

Even though they had not accounted for the driver of Jefferson’s Impala, investigating officers believed at the time of the crash that everyone involved had survived and that Jefferson likely had left the scene. It’s unclear whether any effort was made to locate her in the immediate aftermath of the crash, even after Jefferson’s boyfriend, who had been traveling in a vehicle ahead of Jefferson, returned to the crash site in search of her. Gamble, the police spokesman, has said no one filed a missing persons report for the victims.

Two days after the pileup, on Sept. 22, it became clear that police had overlooked the fatalities. A grass cutter found decomposing bodies of Jefferson and her son just yards away from the crash site in a patch of high grass abutting the Old Gentilly Road on-ramp.

Dr. Jeffrey Rouse, the Orleans Parish coroner, determined both victims appeared to have died from “multiple traumatic blunt-force injuries,” and he classified both deaths as accidental.

Accusing the police of negligence, the elder Gorden said he likely will never know whether his grandson died right away or lay injured for hours at the side of the interstate. “We’ll never know if they were laying down there suffering,” he said.

Follow Jim Mustian on Twitter, @JimMustian.