Police have claimed that the Davidson family members died because of gassing of their place for an intentional apparent-murder suicide.

The dead bodies of two adults and two children were recovered from the property on Monday in Davidson, located in Sydney’s north. They have been identified as 44-year-old Fernando Manrique, 43-year-old Maria Lutz, 11-year-old Elisa and 10-year-old Martin. Reports have suggested that the kids of the couple were autistic.

There were no injuries on the body of the family members, which made the officers think that some poisonous gas was used for the purpose. Along with the humans, a dog was also killed in the incident.

Neighbors, on the other hand, said that they saw Manrique pulling up tiles on his house’s roof but they could not figure out the reason. They did not have an idea that he was constructing a network of pipes to let a poisonous gas pump through their residence. Even the neighbors were shocked to see the incident as the family seemed to be a “happy one.”

Following the evidence, NSW police have started treating the deaths as a murder-suicide. One of the sources from the police department said that “a lot of pre-planning” was done. The officers discovered two cylinders outside the house.

“Whilst the cause of death will be a matter for the coroner to determine, police are looking at the possibility the family members died from the introduction of an airborne gas,” police said. “It is early days in the investigation and investigators will need to wait for toxicology results and results of the postmortems to determine cause of death.”

According to Yahoo News, the failing marriage was believed to be the cause of the Davidson family crime. However, the Facebook profile of Lutz revealed a lot more. She shared her struggles in bringing up two autistic children. She also posted about her joyous family experiences sometimes.