A Sydney woman appeared to have been in a "volatile" relationship with the ex-boyfriend she's accused of murdering in a suspicious fire, police say.
Amanda Zukowski, 46, allegedly knew that Jeffrey Lindsell, 39, was asleep on an October night last year when she lit a fire as well as tampering with the water supply in a bid to hinder firefighting efforts.
The 39-year-old had been at a pub with friends on the Friday night of October 6, before he wandered back to his Gymea granny flat at the back of his elderly parents' home.
Less than two hours later his parents watched their son run out of the burning flat on fire.
Mr Lindsell died of his injuries in hospital two days later.
"It would appear that it was a volatile relationship," Detective Inspector Richard Puffet told reporters on Friday, a day after the accused faced a Sydney court.
"We're still looking into the history of the relationship, there were definitely hostilities in the relationship."
The 46-year-old was charged and faced Newtown Local Court on Thursday, where she was formally refused bail to appear at the same court on August 14.
Police told reporters a tip-off from the public led to a witness with "exceptional evidence".
"There's a wealth of information and evidence that will come out in time," Det Insp Puffet said on Friday.
He described Mr Lindsell as a "well-loved" man who was respected by his family and friends.
He said the Lindsell family was "extremely traumatised" but he hoped the charges would bring them some comfort.
Mr Lindsell's mother Kathy Lindsell tearfully told reporters in February she needed answers.
"Part of us died with him," she said.