More than 20 years later, Ms Ryan - now 40 - has died in central Queensland.
The mother-of-four's body was reportedly found on a Rockhampton golf course on Sunday morning.
Natasha Ryan appeared alive in 2003 after spending five years hiding at her boyfriend's house. (Dave Hunt/AAP PHOTOS)
Police described her death as "sudden and non-suspicious".
Ms Ryan was just 14 when she disappeared in Rockhampton back in August 1998, sparking fears she had been murdered.
A number of women and girls had disappeared in the area at the time, later found to be victims of serial killer Leonard John Fraser.
Her family thought she had died, even holding a memorial service.
Almost five years after she went missing, Ms Ryan remarkably reappeared.
After a tipoff, Ms Ryan was found by police hiding in a cupboard at her boyfriend Scott Black's north Rockhampton residence in April 2003.
Natasha Ryan never explained publicly why she'd hidden at her boyfriend's Yepoon house. (Dave Hunt/AAP PHOTOS)
She was discovered in the middle of the Brisbane trial of Fraser, who had been charged with Ms Ryan's murder.
It emerged that Ms Ryan had willingly kept a low profile at Mr Black's residence, leaving only a handful of times over the years for night trips with her boyfriend to a nearby beach.
Ms Ryan later told police Mr Black - seven years her senior - had tried to get her to go home over the years but she kept asking him to help her.
Mr Black served a 12-month jail term for perjury after lying to a court about his girlfriend's whereabouts.
In 2006 Ms Ryan was fined $1,000 after she and Mr Black were found guilty of causing a false police investigation.
They later married.
Ms Ryan never disclosed why she had run away and hid from family and friends for years.
"I'm never going to say publicly why I left," she told New Idea magazine in November 2007.
"I know why I left. I'm not sure my mum and my sister completely know all the reasons.
"I'm not sure it would make any difference saying why I left - I feel whatever I say wouldn't be good enough for the pain I've caused my family."
Ms Ryan again went missing in Rockhampton on the weekend, sparking a land and air search.
Police said emergency crews discovered the 40-year-old's body in west Rockhampton on Sunday.
A report will be prepared for the coroner.
"I don't know anything more than...the public reporting. This is obviously a tragic story and my sympathies go to her family and loved ones," Queensland Premier Steven Miles said on Monday.
Locals said Ms Ryan would be remembered as a wonderful wife, mother and nurse.
"Fly high Tash, the angels will love you. We all did," Sue Dodt posted on social media.
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