Cody Wilson advocates 3D-printed weapons as a bulwark against gun control and has caused panic by publishing firearm blueprints online. Critics warn that these weapons give criminals access to untraceable firearms.

Taiwan's National Immigration Agency said in a statement that Wilson was caught by the police earlier Friday and handed over to immigration authorities to process his deportation.

Austin Police Department announced Wednesday that the 30-year-old is wanted for sexual assault, saying he was in Taiwan and missed a flight back to the United States.

"The foreigner came legally to Taiwan visa-free but he no longer has a valid passport ... the agency will discuss with the American Institute in Taiwan (AIT) to arrange the return to his country soon," the Taiwan Immigration Agency statement read.

AIT is the de facto US embassy in Taiwan as Washington officially recognises Beijing over Taipei.

According to Taiwanese authorities, Wilson arrived on the island on September 6 and attempted to rent an apartment in Taipei but was yet to move in.

The real estate company that he signed a contract with earlier this month contacted the authorities after watching news about his sexual assault case on TV, police said.

The US investigation into Wilson began after a counselor to whom the victim had spoken notified police "that a juvenile female under the age of 17 had reported having sexual contact with a 30-year-old male."

The victim met Wilson on sugardaddymeet.com, a website that bills itself as the "Best Sugar Daddy Dating Site for Attractive Women and Wealthy Men Seeking Mutually Beneficial Relationships."

Wilson and the 16-year-old had sex at a hotel, and he paid her $500, according to Austin police.

Before leaving the United States, Wilson was informed by a friend of the victim that she had spoken to police, they said.

Wilson published downloadable gun blueprints on his website after reaching a deal with President Donald Trump's administration in June that ended a multi-year effort by the federal government to block him.

But multiple states filed a joint lawsuit claiming Wilson endangered public safety through his actions, and a federal judge issued a temporary order prohibiting the distribution of the digital blueprints.

Wilson -- who subscribes to an anarchist philosophy that the free exchange of ideas on the internet is a check on government -- then said he interpreted the ruling as only barring the free online distribution of the blueprints, and began offering the files for sale.