Sex crimes detectives have used emerging DNA technology to arrest an elderly man for a series of alleged sexual assaults dating back more than 30 years in a first for New South Wales police.

Robert Wayne Kwan, 77, was arrested after detectives issued a search warrant in South Kempsey on the NSW north coast on Wednesday.

Kwan faced court on Thursday on nine sexual assault and several kidnapping charges.

Police allege Kwan was responsible for three attacks over 11 years, involving an 11-year-old girl in Sydney’s west in 1991, a 16-year-old girl in the Illawarra in 1996, and a 26-year-old woman in Dubbo in 2002.

NSW police used forensic investigative genetic genealogy (Figg) to compare DNA profiles from multiple crimes to match genetic profiles – the same technique used in 2018 to identify the Golden State Killer in the United States.

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Unlike traditional forensic profiling, which looks at 21 genetic markers, the Figg process examines hundreds of thousands of genetic markers to identify familial connections as distant as fourth cousins.

DNA markers are compared against two publicly available genealogy databases, GEDmatch PRO and FamilyTreeDNA, which allow law enforcement access to consenting profiles for use in solving serious crimes.

NSW detectives started using the technology in 2022 to review unsolved sex crimes and were allegedly able to link three cases to a single male profile.

In the first case, an 11-year-old girl was allegedly approached in March 1991 by an unknown man in the Sydney suburb of Glendenning, who ushered her into his car after offering her a lift. The man allegedly sexually assaulted her and then dropped her at Mount Druitt railway station.

In February 1996, a 16-year-old girl accepted a lift from an unknown man in Kanahooka in Wollongong. He allegedly sexually assaulted her and dropped her in Warrawong.

In December 2002, a 26-year-old woman accepted a lift from an unknown man near the Commercial Hotel in Dubbo who allegedly sexually assaulted her.

Each of the three alleged attacks were reported and DNA samples were collected.

After DNA analysis confirmed the assaults were linked by the same male DNA profile, police uploaded it to the public genealogy databases, identifying a close relative of the attacker and eventually narrowing their search to Kwan.

It is the first arrest triggered by the technology in NSW.

The sex crimes squad commander, Det Supt Jayne Doherty, urged the public to consider “opting in” on genealogy websites to allow law enforcement to compare profiles.

She said such access is used only for the most serious victim-based offences such as homicides, sexual assaults or to identify human remains.

According to Doherty, other Australian states are using the technology and a previous arrest using the method was made in Western Australia.

“No matter how much time has passed, our detectives continue to pursue every available avenue to identify those responsible for sexual assaults like this.”

Kwan did not apply for bail and will return to Kempsey local court on 22 April.