Juan is deeply upset by the death of his sister and wants to know why the relationship between Family and Community Services broke down," a source close to the family told the Daily Telegraph.
"He was very close to Maria and, as a father himself, adored Elisa and Martin. He longed for them all to come back to Colombia to be close to family."
Police reportedly discovered a network of pipes and gas bottles throughout the home, believed to have been installed by Manrique to gas his family.
Neighbours reported seeing the technology executive working on the roof with power tools over the weekend before the family’s deaths.
"He was right up on the roof replacing tiles and using power tools of sorts,” Neighbour Ofik Thomassian told News.com.au.
"He was cutting and banging and making all sorts of noise and pulling up tiles but I don’t really know what he was doing."
A number of other neighbours have also confirmed seeing the father working on the roof over the weekend.
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