SEATTLE -- The FBI believes that southern California jewelry thieves have moved up the west coast and may be behind an attempted theft in Bellevue on Thursday.

The FBI tells KING 5 News that several members of a Los Angeles crime ring were spotted in western Washington a few weeks ago, casing a jeweler.

Federal agents are now trying to learn more about Sergio Santamaria and two other undocumented immigrants from South America, who appeared in Federal Court Friday afternoon.  They're charged with robbing a jewelry courier.

"He seemed to be targeted.  They seemed to know where he was going and where he had been.  We don't know how he knew that at this point," said Nicholas Brown, assistant U.S. attorney.

The courier was eating breakfast in a McDonald's parking lot when a van boxed him in and masked me held him at gunpoint, smashing his rear window and grabbing a backpack with $500,000 of jewels inside.

It was a sophisticated and precise crime.

"They had some information about where he'd been, his schedule, types of jewels he may have had, and they way they executed the robbery indicated they had some experience.  They've done this before," said Brown.

The FBI has Jewelry and Gem (JAG) units that have been tracking crime rings across the country.

Thursday's victim was a courier from Los Angeles who is in town conducting business with local jewelers.

It's at least the third such robbery in western Washington this year., although they're not all being pinned on the three men in custody – yet.

"It's possible they’re involved in other things, but at this point, we don't know," said Brown.

The feds are tipping their hats to the Bellevue Police officer who spotted the suspect van and caught the three men without incident.  Agents believe there were others involved in the crime who got away.