Pat and Peter Shaw died in their home in Brighton, Victoria in October last year, planning the day in advance and going for a goodbye walk and last coffee with their three daughters beforehand.
They were in their late 80s and their health was failing as they became old, Ms Shaw said. "They were ready, it was their time."
She said she wasn't ready but "I guess you never can be."
Friends of Ms Shaw had criticised her parents' actions, calling them selfish but "seeing them, particularly at the end, I thought no, they're 87. You're allowed to be selfish," she said.
The Shaws were members of Exit International, a pro-euthanasia group run by Philip Nitschke which teaches people peaceful methods to end their own lives.
It was through this group they attained the tools they needed to carry out their deaths without the need to involve anyone else.
The Shaws were adamant they would die together without their children present, to avoid potential legal troubles in the aftermath of their suicide.
"They were very worried about us being indicted in any way," Ms Shaw said.
"If it hadn't been illegal they might have been persuaded to hang around for a bit longer in the knowledge that when it was impossible for them to keep living, in other words become hospitalised, they would have this option. But they didn't have that option.
"What I would have liked is for them to have known they could have done it legally at a time maybe a few months down the track. They were most worried about their ability to take their own lives [and not to] have it taken from them through hospitalisation."
Ms Shaw said her "incredibly rational" scientist parents had spoken about their intentions to end their lives for at least 15 years. "They treated it like scientists as they were, very matter of fact," she said.
"They were always quite adamant they never wanted to be at the mercy of the medicos."
Mr and Mrs Shaw didn't want to go into aged care or palliative care, something Ms Shaw and her sisters thought was very sensible. "They'd been so active their whole lives ... they hated the idea of becoming incapacitated."
When Mr Shaw started having mini-strokes, the urgency of their decision to end their lives with dignity was heightened.
Ms Shaw said the thought of losing physical or mental functions and becoming a burden to anyone was was appalling to her father. "Dad was ready to go about a year ago actually, and started saying he'd had enough."
When her parents announced the date they'd set, Ms Shaw flew home to Australia from Germany to spend time with her parents before their deaths.
She said she had five days with them and despite her efforts to interest them in life again, it was obvious they were ready to go.
The morning they died, a Tuesday, the Shaw family went for a walk, had coffee at Mr Shaw's favourite cafe, said their goodbyes and parted ways.
The Shaw children were instructed to return 90 minutes later and call their parents' doctor.
Due to the nature of the double suicide however, the day became much more fraught than they had intended.
"I guess we hadn't really looked into it but mum and dad had sort of hoped we could get the GP round to certify they were gone and call the coroners but that wasn't they way it worked out, it was a massive crime scene."
Ms Shaw said she was "a mess, in tears," but her sisters held up well.
The three of them had to go down to police station to make statements and the coroners couldn't take their parents' bodies away until 10.30 that night. "The aftermath was for me pretty traumatic and I think my sisters could have done without it too."
Despite this, Ms Shaw said her view on voluntary euthanasia was unchanged.
"I think if I became incapacitated to that level I would [end my life]."
She said her parents never wavered in their convictions, and remembered her father saying: "To all the people who tell us we can't, we can and we did."
Where to get help:
• Lifeline: 0800 543 354 (available 24/7)
• Suicide Crisis Helpline: 0508 828 865 (0508 TAUTOKO) (available 24/7)
• Youth services: (06) 3555 906
• Youthline: 0800 376 633
• Kidsline: 0800 543 754 (available 24/7)
• Whatsup: 0800 942 8787 (1pm to 11pm)
• The Word
• Depression helpline: 0800 111 757 (available 24/7)
• Rainbow Youth: (09) 376 4155
• CASPER Suicide Prevention
If it is an emergency and you feel like you or someone else is at risk, call 111.
