When Walter Mikac lost his entire family, he kept thinking: couldn't he have left me one?

Content warning: This post contains details some readers may find triggering. 

It was the day before his 34th birthday. A Sunday morning like any other.

Walter Mikac kissed his two pyjama-clad little girls and wife goodbye before heading off to play golf.

He was hosting a local tournament on the sprawling greens of a course in Tasmania. His wife, Nanette, and young daughters, Alannah, six, and Madeline, three, decided to have a picnic at the local historic site of Port Arthur where Nanette often volunteered as a ghost tour guide. They planned to meet up later that day.

They never got to meet up. That morning farewell would be the last time he ever saw his family.

Speaking on Wednesday's episode of Anh Do's Brush With Fame, Walter, now 56, recalled what happened that afternoon on Australia's darkest days in history - the Port Arthur massacre -pinpointing the moment he realised his family had been ripped away from him in an unfathomable act of evil.

"We heard shots happening across the bay, because Port Arthur Historic Site was close by, and we were joking, we said, 'Oh, well, they must be having a re-enactment,' was the logical assumption," he told Anh Do. 

"I mean, we're... it's not like you expect anything bad to happen in such a quiet peaceful place. So it wasn't really until after we finished, and we're sitting there maybe having some lunch, three o'clock in the afternoon, where these people rushed in saying, 'There's someone shooting at the historic site,' and there's people been killed.

"Straightaway, obviously, the alarm bells started ringing 'cause I thought, well, I need to go and check this out. I drove home first, and there was... there was no-one home."

Walter jumped in his car and drove to the site, his golf mates by his side, where he was met with the nightmarish result of 29-year-old Martin Bryant's killing spree.

"It was like a war zone. It's hard to...it's hard to describe, really. People were in shock. It was just an awful place to be at that time. And, you know, the gunman still hadn't been apprehended and there was still all this uncertainty about the whole event," he said. 

Then came the waiting.

He remembers pacing up and down the room, his heart sinking in his chest as the clocked ticked on through to early evening, still without answers.

Eventually, a woman named Pam, the local doctor and a friend of the family delivered the news no one wants to hear: Nanette, Madeline and Alannah had been murdered.

"I just want to go as well. My initial thought was I don't want to be here if they're not here. My instinct was to actually run out into the site, and hopefully be ended with... you know, die with them.

"Your body just goes into this spiral of adrenaline and shock and just disbelief. And I had to keep saying to her, 'Couldn't he have even left me one?'" 

Through the depths of his grief, the passionate anti-violence advocate managed to make an impact on the world - he relentlessly campaigned to have Australia's gun laws tightened after Martin Bryant was able to slaughter 30 people with an automatic rifle that Sunday.

He became a guiding force in lobbying for the strict gun control laws Australia is now known for.

Last year, he told Mamamia: "What happened 22 years ago was amazing because I was recently looking back at some old papers... my parents had kept all the old papers from that time... and I noticed on May 11, the gun laws had passed and the gun buy back had begun. That all happened in 12, 13 days.

"I don't think anything could happen that quickly almost ever again, and a few things helped that. One was that John Howard had just been newly elected and had a pretty big majority and then also, the fact the country was just so shocked."

Today, Walter lives and works in NSW's Byron Bay with his 17-year-old daughter, Isabella. The charity he built in the year after Nanette, Alannah and Madeline died - The Alannah and Madeline Foundation - still works tirelessly to protect children from violence.

He still thinks of his wife Nanette and his girls often, and hopes to see them again one day.

"I just wish I could give them another cuddle... You think about all the things that you miss out on over their lifetime... you know, the kids' birthdays, Nanette's birthday, various different things, there's little tricks, songs on the radio, that's so closely aligned to when they were born," he told Anh. 

"Hopefully they're gonna be looking down, if they are, and gonna be saying, 'Dad, thank you. I'm still being remembered [through the foundation]... and I'm helping other children. Our names are being remembered in that way.'"

You can watch the full episode of Anh Do's Brush With Fame with Walter Mikac on ABC iView.

If you or someone you know is going through grief, depression or the loss of a child, please seek professional medical advice, or contact Lifeline on 13 11 14. If you are in immediate danger, call 000.