Bulgarian officials are seeking the extradition of Plamen Vladimirov Trifonov, and U.S. authorities responded to that request by arresting the 58-year-old last week in Kirkland, a Seattle suburb.
The U.S. Marshals Service says in court documents that Trifonov drove a group of Sri Lankan nationals in the cargo area of his truck from Romania to Hungary in 1995. Officials say the truck's cargo area got too hot and restricted airflow, so the passengers punctured a hole in the roof.
Trifonov eventually found that many passengers had died, according to the allegations relayed by U.S. officials in court documents. Officials say he abandoned the truck and the surviving passengers, and authorities later found 18 corpses.
Authorities say Trifonov was involved in another human trafficking incident in 1992 in which 23 people were found in the cargo area of his truck. He was detained by Bulgarian authorities in that case but eventually released, according to records.
In Bulgaria, Trifonov was found guilty of human smuggling and negligent homicide. He was sentenced to eight years in prison in 2002.
Trifonov's court-appointed attorney in Washington state declined to comment.
An extradition and detention hearing is scheduled for the beginning of November. Trifonov was already facing deportation for a 2006 immigration arrest.
The extradition treaty between the United States and Bulgaria went into effect in 2009.