Lauren Goodwin told the Royal Commission into Defence and Veteran Suicide her brother Ryan was a lance corporal in the Australian Army, and after his return from Afghanistan in 2012 he was so profoundly damaged by "the horrors of war" he took his own life in December 2019.

Ms Goodwin, a cardiac nurse, told the commission on Monday she and her family watched on helplessly as her brother's mental and physical health deteriorated to the point they no longer recognised Ryan.

Commissioners heard that after Ryan was discharged from the army, he stopped exercising or eating properly, suffered from "fits of rage", and withdrew from even his closest friends.

He was so tortured by what he witnessed in Afghanistan that he also struggled to sleep.

"When he got back he was not the same person ... but you would get glimpses and you would think, 'Oh my goodness, that would be the most horrific traumatic thing'," Ms Goodwin said.

"It was almost constantly walking on eggshells with him ... he just totally disengaged from everyday life and we begged him to go and seek help. But the more we sort of begged, the more the resistance we were met with."

Ryan's father, Phil Goodwin, told the commission at no point after his son's discharge did they feel he had anything like the support he should have been given.

He said his highly intelligent son had gone from serving in Afghanistan as a crew commander between 2011 and 2012, to fighting to get any help at all from a "very adversarial" Department of Veterans' Affairs.

He said the department treated his son as "just another number there, another statistic, another caseload".

"We miss him each and every day," he said.

Ms Goodwin said in 2018 her brother was so desperate for some sort of relief he started taking drugs.

"He was trying to numb his pain ... just drown out his what he was feeling ... watching my mother crying every day," she said.

"It's absolutely horrible to watch someone dying before your eyes and there is absolutely nothing you can do."

Ms Goodwin said the lack of support for transitioning defence members meant families were left to pick up the pieces alone, leaving veterans feeling as if their army "family" had abandoned them.

"It's like the modern army comrade is almost made to feel like a villain," Ms Goodwin said.

"He very much felt that. There was no welcome home parade.

"How do you go from a very regimented life to a normal everyday civilian life?"

Ryan finally agreed to seek psychological help from the DVA in late 2019, but was told he would have to join a waiting list, the commission was told. Weeks later, on 10 December, he took his own life.

Ms Goodwin said she had been the only member of the family who was able to get to the hospital before her brother died.

She said the siblings at that point had no longer been speaking, but she was grateful she had the chance to tell him how much she and the family loved him.

"He squeezed my hand and I thought, 'Good, he knows I'm here', I'll keep him safe."

After getting her parents and her younger brother Jarrod to say their goodbyes on a phone speaker, Ms Goodwin told him: "You've been so brave we are so proud of you. We love you."

It would take another 18 months after Ryan's death before the DVA confirmed they accepted their liability for Ryan's mental health injuries.

The hearing continues.

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Australian Associated Press