Image credit: Courtesy Christopher J. Morosoff

Relatives of a man who died battling with the Coca-Cola Co. over a stock certificate that would award him a $130 million stake in the beverage maker plans to finish his fight and "see it through," their attorney told ABC News today.

In 2008, Tony Marohn of Indio, Calif., a manual laborer and self-proclaimed treasure hunter, purchased a box of papers at an estate sale.

"It was definitely $5 or less," Chris Morosoff, who represents Marohn's estate, said of the box. "This is what he did. … One find was a big deal to him."

Morosoff said that inside the box Marohn found a Palmer Union Oil Co. stock certificate signed by someone named John Wagner. The line assigning the certificate to someone was blank, so Marohn added his signature.

"It was like a blank check," Morosoff said. "When Tony bought the box, he bought this stock certificate. Whoever holds it, whoever puts their name on it, owns it."

After some research, Marohn discovered that Coca-Cola was the oil company's successor, so he contacted the company in 2009.

Morosoff, however, said the company turned down Marohn's request for stock only after realizing just how much he was seeking - 1.8 million shares of common stock for his 1,625 oil shares.

Eventually, Coca-Cola sued Marohn. It said Thursday that Marohn's claim was "meritless and unfair to the company's millions of legitimate shareholders," according to Reuters.

Marohn died of a heart problem in 2010 and his family took the reins.

"Somebody had to step into his shoes," Morosoff said today. "This consumed a huge portion of his time."

The case was put on hold in February, but Morosoff said that a conference with a judge in Delaware, where Coca-Cola is incorporated, was planned for Monday.

Morosoff said the family - especially Marohn's daughter, Jamie Marohn, the estate's executor, and her mother - believed the stock was valid and planned to continue with the litigation.

"It's not so much about the money," he said. "For my client, for Jamie and her mom, it's about her dad. This was a big deal for her dad before he passed away.  She's going to finish the fight for her dad."