William Swanberg, 40, of Reno, Nev., is accused of stealing hundreds of thousands of dollars worth of the colorful plastic building blocks.
Swanberg was indicted by a grand jury in Hillsboro, a Portland suburb, which charged him with stealing Lego sets from Target stores.
Target estimates Swanberg stole up to $200,000 worth of the brick sets pilfered from their stores in Oregon, Utah, Arizona, Nevada and California. The Legos were resold on the Internet, officials said.
Attempts to reach Swanberg at a county jail, where he was being held on $250,000 bail, were unsuccessful. It was not known if he had retained an attorney.
Swanberg is accused of switching the bar codes on Lego boxes, replacing an expensive one with a cheaper label, said Detective Troy Dolyniuk, a member of the Washington County fraud and identity theft enforcement team.
Target officials contacted police after noticing the same pattern at their stores in the five western states. A Target security guard stopped Swanberg at a Portland-area store Nov. 17, after he bought 10 boxes of the Star Wars Millennium Falcon set.
In his parked car, detectives found 56 of the Star Wars sets, valued at $99 each, as well as 27 other Lego sets. In a laptop found inside Swanberg's car, investigators also found the addresses of numerous Target stores in the Portland area, their locations carefully plotted on a mapping software.
Records of the Lego collector's Web site, Bricklink.Com, show that Swanberg has sold nearly $600,000 worth of Legos since 2002, said Dolyniuk.
Lego's Danish founder Ole Kirk Christiansen named the famous bricks in 1934 by fusing two Danish words, "leg" and "godt" meaning "play well."
Children across the world spend 5 billion hours every year playing with Lego bricks, available in 90 different colors, according to the company's Web site.