The shattered father of the 4-year-old boy found dead next to his mother's body in a Sydney unit says he "never imagined" she would do anything to harm herself or son.
Kiwi mum Stacey Docherty, 38, and her 4-year-old son Seth's bodies were found in the eastern suburb of Hillsdale, after the boy's father and Docherty's ex, Matt Davis, contacted emergency services when he couldn't reach them, the Daily Telegraph reported.
Heartbreaking details of the deaths have started to emerge. Police found words scrawled in blood across walls in Docherty's Hillsdale apartment.
Overnight her sister Rebecca Docherty posted on social media about the heartbreaking loss alongside a musical tribute featuring the melancholic Pink Floyd hit Breathe.
"Love you So much Stacey Docherty! I Love you now until we meet again. I'll find you, hold you, won't let you go you'll be annoyed but I'll know I didn't fail the sweetest soul I ever KNew," she wrote on Facebook.
It is understood the mother and son had knife-related injuries consistent with murder-suicide, but police were not ruling out a third person could be involved.
Davis told the Daily Telegraph he received a text from Stacey Docherty, his former partner, to come around that day to visit, but when he arrived at 1pm no one answered.
He became alarmed and rang police as he thought he could smell gas and could hear Docherty's phone inside when he tried to call.
"I'm shattered about this, I'm trying to piece things together in my head, I wish she would have reached out to me, I feel sorry for her and I hope she is at rest. I'm going to miss my son for the rest of my life," he said.
Davis said his former partner had suffered from a number of mental health issues, along with anger issues related to traumatic experiences she had as a child.
"My memories and thoughts of Stacey were she was a really great mum, she did everything she could for Seth. She did have some mental health issues and now in hindsight there was more going on than what she led me to believe," he said.
Docherty was known to Family and Community Services and police after several incidents, including smashing neighbours cars with a cricket bat.
"[But] there were no indicators that I could see where she had these sorts of things [suicide] in her head. She had never done anything to hurt Seth," Davis said.
"Despite her mental health problems she was a loving mother and a very good and caring person and Seth was a happy little boy."
Davis said he loved his son more than anything and worked to be the best father he could to him.
"Seth was everything to me. When he was born he was the best thing that happened to me," he said.
"I didn't imagine myself being a parent after 45, it was such a joy to have such a beautiful child.
"He was a very happy, bright and energetic little boy who was also very intelligent for his age. I was a very proud father, he was a very personable little boy, he would find friends straight away."
Earlier, the distraught dad posted a tribute to social media.
"I'm going through some GNARLY process but I will get through this," he wrote.
"I feel grateful that for a brief time I got to be a father to a beautiful little boy. Vale SETH BON DOCHERTY!
Davis, who lives nearby in Bellevue Hill, said he had been working to get joint custody of his son.
"I wanted to show him the joys of growing up," he said.
Docherty's Facebook account says she worked as a nursing assistant and that she was originally from New Zealand.
She posted many snaps of her hugging her son and of them playing in a nearby park or at the beach.
Docherty also wrote about being sick of all the "bullshit" in her life and how she was working out what tattoo to get on herself for her son after he was born.
Neighbours have told the Daily Telegraph Docherty was involved in several incidents where police had to be called while living at the apartment on Grace Campbell Cres.
They said Family and Community Service workers were regularly seen checking on them and claimed Seth had been "failed" by the system.
Bidhan Mondal lived near the mother and son and said he was unable to sleep because he was so saddened and disturbed by their deaths, describing him as a "little angel".
"I couldn't sleep at all last night all I could see was the face of the little boy, he was a beautiful little angel," he said.
Mondal said that he had once asked Seth to stop slamming the door because they had a newborn.
Seth never slammed the door again, he said.
Family and Community Services have confirmed they had been working with the family.
"[We are] deeply saddened to hear of the tragic deaths," a spokesman said.
"As this is now a police matter it would be inappropriate to comment any further."
Friends of Davis also posted their condolences on Facebook.
"My heart is breaking for you I cant begin to imagine how you are feeling. May you find some shred of peace in all of this and know that you are so loved by all of those who call you their friend. May Seths little soul rest in peace xxx," one person wrote.
Friends have set up a GoFundMe page to try to raise money for Davis to lay his son and Docherty to rest.
It talks about also creating a legacy for Seth for parents "faced with mental illness who need assistance in parenting".
It said that Seth's birth was the "most amazing moment of Matt's life".
"Many of you know Matt from his long association with the skateboarding and entertainment community," the page states.
"All of you who know Matt know his generosity of spirit, compassion and gregariousness.
"This campaign aims to raise some much needed funds to allow Matt to lay Seth and Stacey to rest."
The Ministry of Foreign Affairs and Trade said they are aware of the death of New Zealander Docherty.
"The Ministry of Foreign Affairs and Trade is aware of the death of Stacey Docherty and her son Seth in Sydney, and is providing consular assistance to the next of kin.
"The family has requested that their privacy be respected during this difficult time."
• Lifeline: 0800 543 354 (available 24/7)
• Suicide Crisis Helpline: 0508 828 865 (0508 TAUTOKO) (available 24/7)
• Youthline: 0800 376 633
• Kidsline: 0800 543 754 (available 24/7)
• Whatsup: 0800 942 8787 (1pm to 11pm)
• Depression helpline: 0800 111 757 (available 24/7)
If it is an emergency and you feel like you or someone else is at risk, call 111.