Steven Lloyd Sadler of Bellevue and Jenna M. White of Renton have both been released from custody pending court appearances later this month.
The secret Silk Road website gained notoriety as a black market drug bazaar that accepted bitcoins, an electronic currency, before federal authorities shut it down last week.
A complaint filed in federal court in Seattle says investigators identified Sadler and White after asking postal clerks in SeaTac to be on the lookout for a woman identified in surveillance video as being associated with certain suspect packages. One clerk managed to get the license plate of her car, which authorities said they traced to Sadler and White's condominium in Bellevue.
They say Sadler was one of Silk Road's top sellers.
Sadler's lawyer said Tuesday he could not comment, and White's lawyer did not return a message from The Associated Press.
Sadler and White were among several people arrested in Britain, Sweden and the United States following last week's closure of Silk Road, a notorious black market website which helped dealers to sell drugs under the cloak of anonymity, officials said Tuesday.
In the U.K., the country's newly-established National Crime Agency warned that more arrests were on the way.
Most if not all the arrests took place within a couple of days of last week's capture of Silk Road's alleged mastermind, Ross Ulbricht, in San Francisco, suggesting that authorities may now be busy unraveling the network of drug dealers who made fortunes peddling illicit substances through the site.
Britain's National Crime Agency said it had seized millions of pounds (dollars) worth of bitcoins, the electronic currency used on the site, and the agency's director general, Keith Bristow, said in a statement that other online drug dealers should expect a knock on their door.
"These latest arrests are just the start; there are many more to come," he said.
Silk Road gained widespread notoriety two years ago as a black market bazaar where visitors could buy and sell hard drugs using bitcoins, a form of online cash which operates independent of any centralized control. A so-called "hidden site," Silk Road used an online tool known as Tor to mask the location of its servers. While many other sites sell drugs more or less openly, Silk Road's technical sophistication, its user-friendly escrow system and its promise of near-total anonymity quickly made it among the best known.
Officials say the black market website brokered more than $1 billion in sales before the FBI collared Ulbricht at a public library on Oct. 1. In its complaint, the bureau said it had managed to copy the contents of the site's server something one expert said would likely provide international authorities with detailed information about the site's dealers.
"Any large sellers on Silk Road should be very nervous," said Nicholas Weaver, a researcher with the International Computer Science Institute in Berkeley and the University of California, San Diego.
Silk Road's eBay-style customer review system means that months' worth of sales history are now in law enforcement hands, Weaver said in an email, while the traceable nature of bitcoin transfers means the FBI "can now easily follow the money."