It is believed he killed Kim, 41, and their three children this week before turning a gun on himself at the family's property near Wagga Wagga in the Riverina.

Detectives working on the case said there had been considerable pressure and tension following the crash, in which Kim Hunt twice flipped her car two kilometres from her Lockhart home in 2012.

After speaking to close friends, police believe "it was more than likely" the ongoing strain made the 44-year-old snap.

Mrs Hunt's sister Jenny Geppert said the family tragedy had left "an indescribable numbness and all-encompassing, heart-wrenching sadness".

"My most beautiful, spirited sister, Kim, whom I idolised and adored; my dear brother-in-law Geoff, who was incredibly generous and kind-hearted; my beautiful nephew and nieces Fletcher, Mia and Phoebe, who I cherished and thought of as my own children," she said on Thursday.

Friends say the family were not under financial pressure and were about to build a dream new homestead on their property, Watch Hill, surrounded by lush wheat and canola fields.

The Hunt family farms most of the land between Lockhart and Boree Creek, and are highly respected within their close-knit farming community.

Mrs Hunt was an intensive care nurse but after a car accident, which left her with a broken neck, seven weeks of post-traumatic amnesia and a brain injury, she had to learn to walk and talk again.

Her speech was still slurred and the family needed in-house carers to help look after children Fletcher, 10, Mia, 8, and Phoebe, 6.

Close family friend Paul Routley said he would never be able to make sense of what happened but wished Mr Hunt had asked for help.

"The stress that's been put on them from the accident was just immense, absolutely immense," he said.

He said Mr Hunt had been a "rock" following the accident, in which Phoebe escaped with minor injuries.

"He was super, super patient. He would help her get out of the car, he would hold her arm. You couldn't get a better bloke. The most gentle, considerate bloke ... a pillar of society."

He said Mrs Hunt had just got her driver's licence back and was working in an educational role at Lockhart hospital. However, her injuries prevented her from doing what she loved most – nursing.

"She was an absolute workaholic. She was very, very dedicated, soft, bubbly and caring."

Mrs Hunt had once said nursing was her "identity" and was frustrated she could no longer work in the wards.

Her sister wrote a heartfelt statement on behalf of her family on Thursday, saying: "All are loved dearly. The void that is left in our lives is immeasurable. They are profoundly missed."

Mrs Geppert, who married Mark Geppert after falling in love on the television series Farmer Wants a Wife, said she had overwhelming support from family and friends.

"I cannot express enough appreciation for this kindness. Thank you."

Homicide police said they were treating the deaths as a murder-suicide and were preparing a brief for the coroner.

❏ Support is available for those who may be distressed by phoning Lifeline 13 11 14; Mensline 1300 789 978; Kids Helpline 1800 551 800.