In the years leading up to his hoax collar bomb attack on a Sydney schoolgirl, Paul Peters started becoming angry and aggressive and "disconnecting from the world" his former wife has told a Sydney court.
Peters, 52, is being sentenced in the Downing Centre District Court over the infamous August 2011 attack, in which he attached a fake collar bomb around the neck of 18-year-old Madeleine Pulver at her Mosman home in an attempt to extort millions from her family.
The court also heard that Peters was suffering from bipolar disorder and a psychiatrist had recommended that he be treated with antipsychotic medication.
Giving evidence in Peters' sentencing today, his former wife Debra Peters said that in 2007 he started drinking heavily, having "mood swings" and "retreating from the world" while they were living together in the US.
"He changed ... stopped being the man I knew," said Mrs Peters who indicated that she continued to support her former husband and considered him her "life partner".
She said that, in the ensuing years, Peters became increasing obsessed with a book he was writing.
The book "began as an historic novel about a man living in Hong Kong" but became "very dark" and disturbing.
The former banker would lock himself away in a room and only emerge to make food or get himself a drink.
At the same time he became "aggressive and bullying" towards the couple's children, a matter which came to a head at a birthday dinner when Peters spat out food on to his plate.
"I said I had had enough of Paul's drinking and his bullying of his daughters and he had to leave," Mrs Peters said, breaking into tears in the witness stand.
In early 2011 Peters went back to Australia, reportedly to complete his book, and continued to withdraw from the world.
In March this year, Peters pleaded guilty to aggravated break and enter and detain for advantage.
According to the police statement of facts tendered in court, Peters told detectives he had been going to the Pulvers' Mosman street for a week before the extortion attempt.
In the mid-afternoon Peters walked through the front door of the home wearing a rainbow balaclava and carrying a baseball bat and a backpack.
He confronted Ms Pulver and then told her: "I'm not going to hurt you."
Peters then removed a black box from the backpack and tied it around his victim's throat with a USB stick and a two-page letter.
In the document, Peters claimed he was a "Green Beret Munitions Specialist" and that the box contained "powerful new technology plastic explosives".
Ms Pulver managed to phone her father, Bill Pulver, who informed police.
Officers rushed to the home but it took a further 10 hours for the bomb squad to be sure that the device was a hoax.
The subsequent investigation hinged on the discovery of a USB stick including a draft demand letter, a silver Range Rover and CCTV vision of Peters buying items associated with the device.
Police eventually tracked Peters down in a small country town in the US state of Kentucky.
Later, forensic psychiatrist Bruce Westmore told the court that Peters said during an examination that he had no memory of the actual crime.
"He recalls walking up the steps of the victim's home, and his next memory occurred back at his home at Avoca 2½ hours later," Dr Westmore said.