An Australian man is under arrest in the United States over the collar-bomb hoax in Sydney two weeks ago.
Madeleine Pulver, 18, spent 10 hours with a fake bomb chained to her neck at the family home in Mosman on 3 August.
The device did not contain any explosives.
The ABC reports a man who went overseas soon afterwards was arrested in the city of Louisville, Kentucky at 4pm on Monday (local time) by New South Wales Police and the FBI.
He is expected to appear in court in Louisville on Tuesday for an extradition hearing.
The Pulver family has told the ABC they are aware of the breakthrough.
The man, 50, reportedly left Australia on 8 August.
The ABC reports police as saying that while the suspect is not directly known to the family, police have discovered links between him and the Pulvers.
h Father welcomes arrest
Madeleine's father, Bill Pulver, made a brief statement to reporters thanking police for their efforts.
He said the family was pleased the arrest had been made and hoped the development would mark the end of a traumatic event.
"This has been a baffling and frightening experience. It has tested us all," he said.