An Australian man pleaded guilty Thursday to putting a fake collar bomb on the neck of a teenage girl in an attempt to extort money from her wealthy family. Paul Peters, a 51-year-old father of three from Copacabana, entered his guilty plea in District Court in Sydney, The (Sydney) Daily Telegraph reported. He is to be sentenced March 16. Authorities said Peters entered the family\'s mansion Aug. 3 and forced 18-year-old Madeleine Pulver to fastened a device with \"powerful new technology plastic explosives\" around her neck with a bicycle chain he secured with a lock. Before leaving the home, he also affixed a two-page document and USB drive and told her to count to 200. She phoned her father Bill and urged him to call police. In the demand note, Peters alleged he was a \"Special Forces Green Beret munitions specialist\" and warned the box could explode. \"You will be provided with detailed remittance instructions to transfer a Defined Sum once you acknowledge and confirm receipt of this message,\" the note said. The crying teenager spent 8 hours with the device around her neck before bomb experts determined it was a fake. Peters fled to the United States five days later and was arrested in Louisville, Ky., Aug. 15. Peters\' attorney, Kathy Crittenden, said her client was \"profoundly sorry\" for what he had done. Bill Pulver said the guilty plea had brought the family closure, although the crime still remained \"a mystery\" and \"random\" to them, the Telegraph said. \"A poor decision by one man has prompted a truly extraordinary and inspiring response from many thousands of people and we will be forever grateful,\" he said.