Michael Anthony Woodhall appeared in the Perth Magistrates Court on Friday charged with 34 offences, including sexually assaulting four women.
Western Australian police used DNA samples coupled with the genealogy technique to identify more than 3500 people.
“We were confident that in those … was our offender,” Detective Acting Superintendent Darryl Cox told reporters.
Detectives worked for two years to reduce the number of genetic matches to one man – Woodhall.
“This has been a painstaking investigation,” Det Supt Cox said.
“Special crime squad used cutting-edge forensic techniques.”
Police alleged the first incident happened about 8.30pm on March 19, 1995 when Woodhall allegedly approached a 49-year-old woman walking in a park.
He was 23 years old at the time and is accused of threatening her with a knife before dragging her into bushland and sexually assaulting her.
The second alleged attack happened about 3am a year later on March 19, 1996, when Woodhall is accused of sexually assaulting a 19-year-old woman in her house.
He allegedly woke the woman before threatening her with a knife and sexually assaulting her.
The third incident occurred at student accommodation near the University of Western Australia about 2am on February 4, 1998.
Woodhall is accused of threatening an 18-year-old woman with a knife before sexually assaulting her.
A fourth woman was attacked at a home in Perth’s east about 2.30am on June 14, 1998, when Woodhall allegedly sexually assaulted a 22-year-old woman.
He has been charged with 14 counts of aggravated sexual penetration without consent, five counts of indecent assault, deprivation of liberty, burglary and a slew of other offences.
He was refused bail and is scheduled to reappear on July 21.
Investigative genetic genealogy uses publicly accessible genealogy databases to match genetic data to ancestors.