The parents of little Elisa, 11, erected a fence around their northern beaches home after she escaped earlier this year, it has been revealed.
She was gone for five hours before anyone found her. On Monday, Elisa, her brother Martin, 10, and her mother and father Maria Claudia Lutz, 43, and Fernando Manrique, 44, were all found dead.
Their bodies were discovered inside their Davidson home, north of Sydney. Police suspect the family, originally from Colombia, was poisoned in a murder-suicide after gas canisters were found around the home.
A friend of the family, who did not wish to be named, told Bogota-based The City Paper, the escape added pressure on the family who wanted to return to Colombia but couldn't because "the children could not travel due to their health issues".
Both Elisa and Martin were autistic.
Manrique was known locally as the loving father who chatted as his two children played with local kids at the park.
He was a high-flying technology executive whose work took him around the world.
But behind the friendly face and the suit-and-tie was a man who turned the family home he built 11 years ago into a gas chamber.
Police were yesterday dismantling the sinister network of hidden pipes used by Manrique to gas his family.
Detectives are investigating the source of the poison found in gas canisters as family members in their home city of Bogota, Colombia, revealed the couple was on the verge of divorce.
Lutz was last seen on Friday after picking the children before having a coffee with other mothers.
BOC gas employees yesterday inspected the property which was rigged throughout the roof to deliver the deadly fumes in what a police source described as an "extensive, elaborate and well planned" operation.
Police are leaning towards the fact that the Drake Business Logistics company executive acted alone but have not been able to rule out the possibility of a murder-suicide pact with his wife.
"We may never know whether she knew what was happening, we just don't know," a source said.
Police are also investigating "domestic tension" between the couple as relatives' tributes on Facebook pointedly made no mention of Manrique.
A source close to Lutz, who wished to remain anonymous, has told The City Paperthat the relationship between the couple was "at times very tense due to the stress of bringing-up the children".
The source said Manrique had "become very distant" and that his wife felt "very alone" but they could not confirm that she was filing for divorce and custody of the children.
Computers were seized from the house to see if Manrique had been researching the gassing and for any hint Lutz knew about it.
Maria had previously told of the sleepless nights and battles she endured raising two children who both struggled with non-verbal autism, but frequently told friends they were "my life".
The couple, who left Bogota for Australia and have no immediate family in the country, arrived in Davidson in northern Sydney in 2005.
Close friend Peta Rostirola described Maria as "selfless" in the battles she fought raising autistic children: "You faced life head on with all the challenges it threw."
Maria campaigned tirelessly for children with autism and often volunteered at St Lucy's school's fundraisers.
St Lucy's principal Warren Hopley honoured the woman who "touched the lives of so many". "We are all struggling to come to grips with this profound tragedy," he wrote.
"Elisa, Martin and Maria have been such a source of inspiration for us all at St Lucy's over the years.
"I have been bombarded with expressions of support and love. Maria touched so many people's lives."
Where to get help:
• In an emergency: call 111
• Lifeline: 0800 543 354 (available 24/7)
• Suicide Crisis Helpline: 0508 828 865 (0508 TAUTOKO) (available 24/7)
• Youthline: 0800 376 633, or text 234 (available 24/7) or email@example.com or live chat (between 7pm and 11pm) http://livechat.youthline.co.nz/mibew/chat?locale=en&style=youthline
• Kidsline: 0800 543 754 (available 24/7)
• Whatsup: 0800 942 8787 (1pm to 11pm)
• Depression helpline: 0800 111 757 (available 24/7)