At first, he doubted the claim of digital quality, so the peddler popped a copy into a portable player. “I said, ‘Wow,’ ” Mr. Sanchez recalled. Hepaid $5 and took the disc home.

Image Gilberto Sanchez, a glass installer and musician, posted a bootleg copy of “Wolverine” on the Web and has since been charged with violation of copyright law. Credit... Librado Romero/The New York Times

After watching it with the grandchildren, he made a copy on his computer and posted it on megaupload, where his screen name is “SkillyGilly,” so others could share in the fun and he could get props in the movie-loving community. He ignored a friend’s warnings  “You’re going to get in trouble; it’s not even out yet”  and watched as several other copies surfaced on the site.

At 5 a.m. the next day, that friend called and told him to turn on the TV.

“Fox News is in an uproar for the leak of ‘Wolverine,’ ” Mr. Sanchez recalled. “They’re offering a reward.” By then, he said, his copy of the movie had been downloaded 198 times, at no charge.

He was scared, but did not imagine he would be blamed. “Some employee had it  ‘Hey, take this down to graphics’  and he stopped off and showed it to his friends,” Mr. Sanchez said. “They made more copies, more copies, until the Koreans had a copy.”

Two weeks later, the F.B.I. showed up, having tracked “SkillyGilly” through computer footprints. Mr. Sanchez said he explained what had happened. “Talk to the Korean,” he said he told them. “You keep following leads and you’ll get to a warehouse.” But when the F.B.I. asked if he could identify the peddler, he said no.

A few months later, agents took his computer, then returned it, he said. Several months passed, and then the agents were back with an arrest warrant. Wesley Hsu, an assistant United States attorney for the Central District of California, who is supervising the prosecution, said financial gain is not necessarily the sole motive for so-called pirates.

“It’s some sort of Internet prestige thing,” Mr. Hsu said. “That’s sort of how the culture works.”

Mr. Sanchez, who speaks to rehabilitation groups  “I’m Gilberto Sanchez, I’ve been to jail, I’ve been through this, I’ve been through that”  said he has no intention of fighting the charge. “I can’t say no,” he said, pointing to his computer. “That’s like DNA.”