Prosecutor Katarina Lenter says the diplomat left Sweden earlier this week after the Foreign Ministry declared him persona non-grata. She says the motive for the suspected kidnapping plot was that he didn't approve of his daughter's boyfriend in Sweden.
Lenter told AP on Friday the man could not be prosecuted because of his diplomatic immunity but an alleged accomplice, who is not a diplomat, is being held in jail pending possible charges.
Swedish news agency TT reported the daughter was 18 and living in a secret location.