Heartbreaking photos show siblings, 3, 5 and 7, beaming alongside their mum before she slaughtered them and killed herself in horror murder-suicide - as dad refuses to answer calls from loved ones

A mother and her three children were pictured smiling together at a family picnic just weeks before she killed them and herself in a tragedy that has shocked Australia.

Mother-of-three Katie Perinovic, 42, and her children Claire, seven, Anna, five, Matthew, three, were found dead at their Tullamarine home in Melbourne's north after midday on Thursday. 

Husband and father Tomislav Perinovic, 48, found the bodies and raised the alarm with a harrowing Triple Zero call at 12.20pm. 

Detectives said Mr Perinovic was not involved in the incident, and he has been released without charge after being held overnight for questioning.   

Pictures have since emerged showing the mother and her children at a park picnic and baking at home before what police described as their 'gruesome' deaths on Thursday.  

Mother Katie Perinovic and her children (left to right) Matthew, three, Anna, five, and Claire, seven, were found dead at their Tullamarine home in Melbourne's North at midday on Thursday 

Father Tomislav Perinovic , the children and Ms Perinovic. Mr Perinovic has been released without charge

Another picture shows sisters Claire and Anna beaming for the camera as they ate lollies together. 

Close family friends Frankie and Sanja Franjic visited the house to offer their condolences to Mr Perinovic on Friday. 

But the shattered dad was not there and they have not been able to reach him.

'He's (Mr Perinovic is) not answering calls. He's heartbroken… that's why I want to talk to him,' Mr Franjic told The Herald Sun. 

'The father, he was the most loving father ever; he would spend more time with the kids than with Katie.' 

Mr Perinovic is suspected to be staying at his parents' home as he mourns the deaths of his children and wife. 

Mr Franjic said Katie was in good spirits at his grandson's birthday two months ago, which is when he last spoke to her.   

He said the murder-suicide 'just came out of nowhere… what brought this on? No warning signs at all'. 

Next-door neighbours Daniel and Vicky Schembri were at home at the time the four bodies were found. 

Ms Perinovic called the couple to give them some fruit less that 24 hours before the tragedy.    

Claire, Anna and Matthew (left to right) are pictured baking with their mother 

Another picture shows sisters Claire and Anna smiling as they ate lollies before they were found dead this week 

After nearly two days of investigations, police on Friday revealed they believe Ms Perinovic killed herself and the children.  

Victoria Police investigators said Ms Perinovic likely killed Claire, Anna and Matthew and herself at their Tullamarine home. 

'Homicide Squad investigators have formed the preliminary view that the 42-year-old woman is responsible for all four deaths,' a police statement said on Friday.  

'Investigators do not believe the 48-year-old man was involved in the incident and police are not looking for anyone further in relation to the matter.' 

The shattered father is pictured with his children and wife - who killed all three and then herself 

A note and flowers are left outside the family home in Melbourne's north following the tragedy

Homicide Squad detectives aren't looking for anyone further over the deaths and a report will be prepared for the coroner. 

Kevin and Clare Harrison, who live opposite the family, cried when they heard the news about their neighbours.

'We shared coffees, we have sat on their front veranda and just laughed at the kids and the way they just ran around in the yard,' Mr Harrison told The Australian.

'I used to talk to Tom while he was teaching Matthew how to ride a bike … everyone around here was involved with them because of the kids.

'Christmas Day, every year we have given the kids Christmas presents because we have known them from birth.'

A heartbroken friend of Ms Perinovic said she was notably 'withdrawn' in the weeks leading up to the deaths.   

Marie Groves, a neighbour, had become close to her as their children often played together.

Crime scene cleaners arrived at the well-maintained home in hazmat suits and forensic gloves on Friday

Children's drawings were seen stuck on the window at the scene of the awful tragedy 

She said the mother attended a party at her house for her daughter's birthday in November, and was unusually quiet.

'She was more withdrawn than I've seen her ever in the past,' Ms Groves told Daily Mail Australia. 

'There were a few other mums here and they did notice she seemed a bit quiet on that day.'

Ms Groves said: 'Those kids were full of life. They were your picture perfect kids.'  

Police said there was no history of family violence involving the family. Pictured: Katie and Tomislav Perinovic with their daughter 

Mourners pay their respects at the home in Tullamarine on Friday, above

Bouquets were piling up out the front of the blond-brick property on Friday morning

Others who knew the mother said she often visited the local library with her young kids and would lovingly sing songs and read to them.   

The crime scene was described as 'gruesome' by police, who did not go into detail about the nature of the family's injuries.

Ms Perinovic, who also goes by the surname Blazevic, unexpectedly left her job at Glenroy Physiotherapy Centre about three months ago, The Herald Sun reported. 

Neighbour and friend, Marie Groves, said Ms Perinovic was very 'withdrawn' and quiet when she saw her at the end of November at her daughter's birthday party

It's believed she may have fallen into a depression in the lead up to her death.

She had worked at the clinic for seven years, according to the website. 

Neighbour Ms Groves said that she still hadn't processed the shocking news of the family's deaths.

'It hasn't sunk in that I'm not going to walk out the door and see her walking past to the milk bar and picking up pizzas with the kids,' she told the ABC. 

'She was Katie, smiley face Katie, who would always stop and chat.'

Another neighbour John Constantino said he chatted with the mother-of-three the night before she died and noticed nothing out of the ordinary.

'I was watering the garden about 7.30pm and she walked past and she seemed happy and everything,' he told The Age.

'She asked me what I was going to do tomorrow, I said, 'I might mow the lawn' and she said 'yeah, it's not going to be a hot day'.' 

Neighbours were left devastated upon hearing the tragic news of the well loved family

A mourner leaves flowers at the home in Tullamarine after the tragedy on Thursday

Cleaners are seen arriving at the home in Tullamarine as investigations into the deaths continue

Officers who were called to the scene in Tullamarine stand with police tape on Thursday

The father appeared 'extremely distressed' on the street when emergency services arrived. 

Residents have been left shocked by the deaths which have rocked what they describe as a quiet area. 

Tara Jenkins, who lives around the corner from the family, said she was 'absolutely gutted' by the 'devastating' turn of events.

Emergency crews were called to the house in Tullamarine, Melbourne's north-west, on Thursday afternoon

'Those kids were so young, just beautiful little kids. 'Their was always alone with them and was a very loving mother,' she told The Age.

'We would often say hello to each other as our kids played. She was always really cheerful and kind ... just a lovely woman.'

A neighbour who lives next door said he heard the commotion of the emergency crews but was advised to stay inside.  

'It's a bit too much for a local neighbourhood like this,' another said. 

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