The father who killed himself and his toddler son during a planned custody visit had set up a deadly poisoning system inside his home, police believe.
The man, 38, and two-year-old boy were found dead inside a unit on College Street in East Lismore on the NSW far north coast on Sunday night after police were called to perform a welfare check.
The boy’s mother raised the alarm after the boy failed to arrive back at her home as planned on Sunday afternoon and was unable to make contact with the father
The father of the child, who was known to police for domestic violence matters, is understood to have killed his son before he took his own life.
Detectives are investigating whether carbon monoxide poisoning contributed to the pair’s deaths, the Daily Telegraph reported.

Police are investigating whether a fatal poisoning system may have led to the deaths of a father and a toddler, who were found deceased at a unit in in East Lismore, on the NSW Far North Coast (pictured), around 9.45pm on Sunday
It’s understood forensic crime scene specialists found equipment and a set-up inside the premises consistent with carbon monoxide poisoning.
A post mortem examination will be carried out this week to determine how the man and the toddler died.
High levels of carbon monoxide can cause a loss of consciousness and seizures which can lead to death.
The toxic gas, which is odourless and colourless, is made by burning petroleum substances such as oil, diesel, and petrol.
Daily Mail Australia doesn’t suggest these substances were involved in the pair’s deaths.
Detectives and crime scene officers donning protective gear and face masks spent most of Monday scouring the two-bedroom unit and left the complex with several bags of evidence.
A small red tricycle could be seen sitting in the carport taped off by police.
It’s understood the unit block had recently been refurbished following extensive damage in the 2022 floods.

Crime scene officers (pictured) were seen leaving the unit on Monday carrying bags of evidence, after they scoured the property

The father, who was known to police, is understood to have killed his son before he took his own life. Children’s bikes were seen outside the unit on Monday
Deputy Police Commissioner Peter Thurtell said detectives are aware of how the pair died and there was no weapon involved.
‘The father has created a system where both he and the child have passed away as a result of the system he set up,’ he said.
‘A more tragic event you wouldn’t come across.’
Deputy Commissioner Thurtell said the man was known to police for previous domestic violence matters but not ‘significant issues’.
He said the mother was living in the local community with her son, who was an only child, and the father had an access visit on Sunday.
‘The mother raised concerns [to police] with the fact they were due to hand over the child at 4.30pm and by 5.30pm she had contacted police and we went round to the residence and made the discovery,’ Deputy Commissioner Thurtell said.
It is understood the mother of the child had an Apprehended Violence Order out against the father.

Deputy Commissioner Emergency Management Peter Thurtell (pictured) addressed the media on Monday following the incident
The incident has rocked the neighbourhood.
Shocked neighbours told the Daily Telegraph that they occasionally saw the boy in the street but did not hear anything untoward or sinister on Sunday.
‘I don’t think the child went there all that much…but I did see him with (the child) not that long ago but it all looked normal enough,’ one resident told the publication.
Another neighbour Lucy met the ‘sweet’ and ‘shy’ boy when his father moved into the complex around six months ago.
‘When they first moved in, they saw my cat and they came around and were playing with him… he was a bit shy, the boy, but he just wanted to play with my cat,’ she told ABC News.

Forensics teams (pictured) spent most of Monday scouring the unit for evidence
Locals have rallied around the boy’s grieving mother and took to social media to mourn the loss of the toddler
‘To that poor, poor, mother… my heart breaks for you,’ one wrote
Another added: ‘Unimaginable what that mum is going through. Rest easy, little one.’
As investigations continue, anyone with information about this incident is urged to contact Crime Stoppers on 1800 333 000.
For confidential support 24/7, contact Lifeline on 13 11 14 or Beyond Blue on 1300 22 4636