Kararaina Brown says the heartbreak of always looking for a loved one who hasn't come home never stops.
The Rotorua woman says her family is feeling for Nigel Peterson's family as they know the torment of not having closure.
Kararaina's sister, Te Whai Brown, went missing on March 21, 1996 near Rotorua.
Although a coroner has officially ruled she is dead, they have never given up hope of finding her alive.
That horrible, empty feeling in the pits of their stomachs has been with the Brown family since Tewhai, 31, was last seen walking along State Highway 33 towards Tauranga from her family home at Okere Falls.
There were more than 30 sightings of her, including from road workers who said she was in good spirits dancing and singing along to a yellow radio she was carrying.
Kararaina said the mother-of-six had been a happy and humorous woman all her life but in recent months leading up to her disappearance she had been in a bad place as a result of a relationship breakdown and was suffering from depression.
The Brown family had always suspected Tewhai was picked up by someone and something awful had happened to her. But they will never know the truth until they find her body.
"The awful thing is you look at people differently. When you meet someone you think to yourself 'did you take her?'," she said.
It was not knowing exactly what happened that hurt the most.
"The heartbreak doesn't stop and you carry it for the rest of your life. We know she is dead but that doesn't stop us hoping someone will come forward with some information that would help.
"I feel sorry for Nigel's family and it would be devastating and they will feel like this for many years unless someone or something comes through. I pass on my condolences and my thoughts to them."
Coroner Wallace Bain ruled in 2010 that Tewhai probably died around March 22, 1996, when she went walking and got into a "state of exhaustion''.
"The cause of death is undetermined but it is likely she met an accident or misfortune as she wandered off the highway and that caused her death - likely from exposure,'' Coroner Bain said at the time.