An Australian man is being held in the US state of Kentucky on charges he locked a fake bomb around the neck of a Sydney teenager in an extortion bid.
Paul Douglas Peters, 50, was detained pending extradition as startling details emerged about 18-year-old Madeleine Pulver's ordeal on 3 August.
Australian and US investigators traced him through an email account he hoped to use in ransom demands, police said.
A lawyer for Mr Peters said his client would fight the charges against him.
He was arrested on Monday at his ex-wife's house near Louisville, Kentucky, following a short but intensive investigation spanning two continents.
A chain of evidence based on forensic computer clues, transnational banking records and immigration records, among other things, traced his movement from the Australian state of New South Wales to the US, prosecutors said.'I can see you'
In a federal court in Louisville on Tuesday, US Magistrate Judge Dave Whalin ordered that Mr Peters be held in custody until his extradition hearing on 14 October.