For Gwendolyn Pasos, absorbing the news that her grandson had been fatally shot during his shift at a Walmart store on Monday was about all she could handle.

But two days after the killing, Pasos said her family was still struggling to make sense of what happened in the final moments of 28-year-old London McKnight’s life — and why.

Pasos said Wednesday that she and her relatives had heard that a disgruntled customer may have slain McKnight. They were hoping that either police or her grandson's employer, where he had worked for roughly seven years, would clarify what led to the bloodshed.

“We are still in the dark about everything surrounding this situation,” Pasos said. “We don’t have the correct story of what happened.”

As Pasos heard it, her grandson’s killer — identified by police as 21-year-old Kentrell Banks — may have been trying to return some merchandise without a receipt at the Chef Menteur Highway store when a cashier summoned McKnight, an assistant manager, from his office.

McKnight either wouldn’t or couldn’t allow the return, so Banks either pulled out a gun that he had on him or went to get one and pointed it at McKnight, according to that account.

+2 'Everything revolved around his son': Man killed in Walmart shooting was dad, asst. manager The man who was fatally shot while working at a Walmart store in Gentilly on Monday night was an assistant manager who leaves behind a young s…

Pasos understands that people watched as McKnight gasped, “Oh, Lord,” and tried to duck behind the cash register. But before he could get out of harm’s way, he was shot in the chest and mortally wounded.

Whatever happened, neither authorities nor Walmart officials have been willing to share what they know with Pasos or her family, she said.

A Walmart spokesman didn’t respond to a request from this newspaper for comment, beyond a statement on Monday expressing condolences to McKnight's family. Police on Wednesday said they couldn’t elaborate on the case because it remains under investigation.

In an initial statement, police said McKnight appeared to be assisting Banks when Banks shot him.

Court records that investigators filed later say only that surveillance video from the store shows Banks entering through the main door, walking up to McKnight at a register and firing a handgun at him. A bystander was also struck in the foot.

McKnight died at the scene while Banks — still holding the pistol — headed for the exit.

An off-duty police officer who was working a security detail at the store saw the shooting and cut Banks off, the court records said. The officer ordered Banks to the floor and handcuffed him.

Police booked Banks on counts of second-degree murder and attempted murder, and he remains in custody in lieu of posting $500,000 bail.

Pasos, McKnight’s maternal grandmother, said one of her grandson's co-workers first alerted the family to what happened Monday night.

Since then, Pasos said, she’s been grieving for the boy who was raised by his mother, his grandmother and an aunt.

According to Pasos, when McKnight turned 15, he began working — while continuing his studies — to add some income to the household. He eventually decided to work full-time at Walmart and try to climb the corporate ladder there because he believed it gave him the best shot at supporting his family.

That became an especially important goal for him when he had a son five years ago with his childhood sweetheart. Though the couple were no longer together, Pasos said they worked together closely to raise London Jr. — the child who was the reason for everything McKnight did.

McKnight also was a loyal sibling to his brother Italy and sister Paris. In one of their last conversations, the siblings discussed making matching T-shirts with images of the places for which they were named.

“Our heart is gone,” Pasos said. “London, Paris and Italy were like three parts of a triangle. And now one part is gone, so we’re incomplete.”

Before his bail hearing Tuesday, Banks filled out a financial declaration that listed no employment and said “SSI” — supplemental security income — was his only source of income.

Pasos said she saw Banks' mother tell WWL-TV that Banks had long been struggling to get mental health help. Pasos said she regrets that Banks was unable to get whatever assistance he needed before Monday night.

“There's nothing now ... that can bring our son back to us,” Pasos said.

Pasos asked the public to consider donating to a GoFundMe campaign that was established to provide support for his family.