A MOTHER involved in an argument with her daughter is the prime suspect in killing her three children before setting her house on fire and committing suicide.
Kylie Maher, 36, and her eldest daughter, Sammantha, 18, became embroiled in a fight after the teenager turned up at the Heidelberg Heights house with her boyfriend on Sunday afternoon.
In frenzied scenes, the boyfriend, who was pushed away from entering the back door by Ms Maher, saw the pair argue before trying to get neighbours to help in force his way in.
It is not known if her other children, Melanie, 13, and Matthew, 11, were alive.
The coroner has found both Sammantha Fowler, who lived in Skye, and her half brother Matthew had injuries consistent with a sharp object, such as a knife.
Police are also working towards the theory Ms Maher, who also went by the surname Fowler, lit a fire in the kitchen area that ripped through the house and burnt their bodies.
He then went to the neighbours house directly behind in a desperate bid for help.
He has told police he returned to see his girlfriend badly bleeding and again tried to force entry as the fire began to take hold.
The four dead family members were located within three different rooms in the house.
Police and Metropolitan Fire Brigade crews arrived shortly after 4pm and forced entry into the brick veneer house but were unable to help any of the badly burnt people inside, who were deceased.
Police are awaiting further forensic analysis to determine the exact cause of the fire, however it is deemed suspicious and at this stage it is believed a type of accelerant was used.
A friend of Sammantha said the teenager, who finished year 12 at Carrum Downs secondary college last year, was kind-hearted.
“She cared about all her friends and family,” the friend said.
“She pretty much just wanted to live her life to the full.”
Theresa Waters, who knew Matthew through his involvement in the North Heidelberg Junior Football Club, said the 11-year-old was a “good kid”.
“You had to check if he was actually there because he was so quiet,” Ms Waters, 34, said.
“He never made a fuss over anything.”
Ms Waters said Matthew had played at the club for two seasons.
“He loved his footy,” Ms Waters said.
“He kicked a few goals in the very last game he played.”
An exact cause of death is still not known and toxicology reports are expected take up to eight weeks.
Investigators have now finished processing the scene on Southern Rd.
Police have spoken with a number of witnesses and are urging more to come forward.
The arson and explosives squad is investigating the matter and will now prepare a brief for the Coroner.