Paul Ceglia, who claims in a lawsuit that he owns 84 percent of Facebook Inc., said his case wouldn’t have been possible if state troopers hadn’t come to his house in October to arrest him for fraud.

Ceglia’s arrest and a suit by New York Attorney General Andrew Cuomo two months later, both the result of complaints related to his startup wood-pellet business, got him looking through old files to find assets to pay back customers, he said in an interview in his home in Wellsville, New York. One of those files held a forgotten 2003 contract with Mark Zuckerberg, now chief executive officer of Facebook, he said.

Ceglia, 37, a self-described environmentalist from western New York who wants to legalize drugs and has views on the evils of central banks, claims the contract entitles him to most of the company. If true, the claim, which would give him control of the world’s most-popular social networking service, would be worth about $21 billion, given estimates of the company’s value.

“If this thing hadn’t happened the way it happened, no way I would have ever started looking through these ancient folders,” Ceglia said of his pellet problems. “That contract would just be sitting in there gathering dust.”

In the weeks since Ceglia came to public attention with his lawsuit against Palo Alto, California-based Facebook and Zuckerberg, filed June 30 in New York state court, observers have been asking why he took so long to make his claim. His answer, it turns out, was he forgot about it.