A 4-year-old boy and a young mother who were found dead last week alongside Interstate 10 in Gentilly had been killed in a crash two days earlier that involved six vehicles, New Orleans police said Thursday.

But more than a week after a grass cutter discovered the bodies, decomposing in a patch of high grass abutting the westbound on-ramp at Louisa Street, a host of questions remain about the deaths and why it took more than 48 hours for the bodies to be located.

Police said the case remains under investigation and declined to release specifics about the Sept. 20 crash that they believe took the lives of Tracey Jefferson, 28, and her son, Richard Gorden III.

“The fatality unit is still investigating it, as far as exactly what happened,” said Tyler Gamble, a Police Department spokesman.

He added that no warrants have been issued in the case, which is no longer being investigated as a hit-and-run. The crash had been listed as a hit-and-run in the city’s online database of emergency calls for service.

The boy’s grandfather, Richard Gorden Sr., said family members haven’t received any updates from investigators, leaving them to imagine various scenarios in which the victims may have perished.

It’s not clear, for instance, whether Jefferson and her child were ejected from a vehicle or were struck while walking alongside Interstate 10. Police have not released an initial copy of the crash report.

“I’m in the dark about what’s really going on,” Gorden said. “They haven’t told us anything about the crash. (Jefferson) and the baby just disappeared, and their bodies were found that Monday evening.”

In a statement released last week, Dr. Jeffrey Rouse, the Orleans Parish coroner, said both victims appeared to have died from “multiple traumatic blunt-force injuries.” Both deaths, he added, had been preliminarily classified as accidental.

It was clear from early on in the case that detectives thought the deaths could be traffic-related. A team of investigators responding to the scene Sept. 22 walked along the shoulder of the interstate, combing the guardrail for clues. At one point, several of them homed in on a section spanning several feet and appeared to be collecting evidence.

Jefferson’s boyfriend, Kristian Donsereaux, said in a brief phone interview that he witnessed an early morning “pile-up” on the interstate the Saturday before the crash, and that he “wouldn’t be here right now” if he had been riding in Jefferson’s vehicle. Donsereaux said he had no idea what happened to his girlfriend after the crash, alleging that police “didn’t investigate her at all, or that car.”

“Basically, it was a wreck,” said Donsereaux, who declined to elaborate on the circumstances of the crash. “I don’t know how they ended up where they ended up at.”

Donsereaux showed up at the police perimeter around the site shortly after the bodies were found, speaking at length with officers and pacing in agitation.

He told WDSU-TV last week that Jefferson had attempted to swerve around a stalled car but was struck by several vehicles. “They just kept on hitting her and hitting her,” he told the station. “We couldn’t stop right then and there.”

Donsereaux told WDSU he returned to the scene immediately and couldn’t find Jefferson. But, in the same interview, he added, “I should have got out and ran back down the interstate. I probably would have gotten hit, too, but maybe the outcome would have been different.”

Gorden, the grandfather of the 4-year-old boy, said a memorial service for the victims, who were buried last weekend, is scheduled for noon Friday at Reaping the Harvest Church, 5123 Dauphine St.

He said he will remember his grandson as an indefatigable bolt of energy, a happy child who enjoyed playing with balls and who was looking forward to attending school.

“He touched our lives,” Gorden said. “I don’t know what the reason is that he has left. Only God knows that.”

Follow Jim Mustian on Twitter, @JimMustian.