Czech authorities suspect that Kevin Dahlgren fatally stabbed his aunt, uncle and two cousins in the city of Brno during his May 2013 stay. Authorities said the victims had been stabbed in the head and neck, and it appears that he tried to burn three of the bodies.
Dahlgren was detained briefly on May 23 at Washington Dulles International Airport as he returned to the U.S. after the visit.
Justice Ministry spokeswoman Tereza Schejbalova said Dahlgren arrived in Prague on Monday and was transported to a court in Brno, the Czech Republic's second-largest city, to decide if he stays in custody pending his trial. A hearing hasn't been set.
The ministry said in a statement that Dahlgren is the first U.S. citizen to be extradited to the Czech Republic.
"I appreciate the decision by (U.S. Secretary of State) John Kerry who approved the extradition of K.Dahlgren," Czech Foreign Minister Lubomir Zaoralek commented on Twitter.
If convicted of committing four murders, Dahlgren would face up to life in prison. He might be able to serve his possible sentence in the U.S. That would have to be approved by the Justice Ministry.
For the last two years, Dahlgren has been fighting extradition in U.S. courts. Among other arguments, Dahlgren's lawyers claimed that no extradition treaty was in force between the U.S. and the Czech Republic because the original extradition treaty was signed between the U.S. and Czechoslovakia, which no longer exists.
On Aug. 25, a federal appeals court in Richmond, Virginia, refused to intervene on Dahlgren's behalf, allowing the U.S. State Department to go forward with the extradition.
The State Department, in a letter to Dahlgren's attorney, said it will provide Dahlgren regular consular visits and monitor his trial.