More than 35 years after killing their parents, Erik and Lyle Menendez have been recommended for re-sentencing by the Los Angeles County District Attorney.

The 1989 case shocked the nation, with claims during the trial that the brothers were abused by their father physically and sexually met with scepticism at the time, while their $US700,000 ($1 million) spending spree after the killings was suggested as an apparent lack of concern about what they had done.

Amongst the spending spree — which included new cars, new clothes, and new watches — was a purchase of courtside tickets to watch the NBA's New York Knicks in action at Madison Square Garden.

It was a decision that would immortalise the brothers in the basketball world in a grim coincidence only noticed decades later.

Crime writer Stephen Zerance, knowing the story about how the brothers had attended the basketball after the killings, went on a search in 2018 to see if he could find them in the background of action photos.

"My friend and I, who is also a true-crime head, knew that the brothers went on a lavish spending spree after they got an insurance payout from their parent's death," he told basketball magazine SLAM in January, 2019. 

"They bought a lot of things — tennis lessons, Rolexes, clothes, businesses, restaurants, cars. Then we noticed they bought courtside tickets to the Knicks at Madison Square Garden.

"When Getty Images didn't have [any photos], it was like a light bulb. There are so many junk [basketball] cards on eBay."

Hunting through the web for basketball cards from the 1990 season, Zerance stumbled upon one of point guard Mark Jackson.

In the background, to the left of his hip, were the brothers watching the game, pictured after they had killed their parents and before their eventual arrest.

It was a discovery that had Zerance wondering what else lurked in the background of photos at sporting events.

"I'm sure this will continue happening," Zerance said. 

"There have to be so many things hiding in plain sight."

Zerance purchased several of the cards for 10c each.

According to card trading website sportscardinvestor.com, a card can sell for as high as $US800 ($1,200) depending on the quality and the grading.

Often, true crime fans are the people buying the cards, rather than basketball fans.

According to The Washington Post, in late 2018 and early 2019, eBay took down listings of the card because of their policy against selling items "affiliated with murders or serial killers".

The removal has since been revoked.

For his part, Jackson — who went on to become a broadcaster for ESPN and coach of the Golden State Warriors — said he was aware the brothers appeared in the back of the card.

"I always knew about it, unfortunately, because of the history behind it," he said. 

"[I] heard about it whenever it picked up steam. People recognised what it was all about and who was in the background. I'm well aware of it."

Zerance, who posted the card on Twitter in 2018, said the discovery didn't go viral until later in the year, when an anonymous Reddit user posted it.

"I'm just glad it went viral, really. It's a cool little tidbit," he said.

The Menendez case is set to be heard by a Los Angeles judge, who will decide whether the brothers' sentencing will be downgraded from life without parole.