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The man at the center of the controversy over 3D-printed guns was arrested Friday in Taiwan after being accused of having sex with an underage girl in Texas, according to CBS News.

Cody Wilson, who runs Defense Distributed, which designs and distributes programs to print guns, was charged on Wednesday with having sex with an underage girl and paying her $500 in Texas, according to Commander Troy Officer of the Austin Police Department. A friend of the 16-year-old girl told Wilson that police were investigating the alleged child sex assault case, Officer said.

It's unclear why Wilson traveled to Taiwan. He didn't immediately respond to a request for comment.

"The US Marshals Service is aware of Cody Wilson's arrest," a US Marshals Office spokesperson said in an email statement, on behalf of the Austin Police Department. "We are fully engaged with our international partners on this matter."

Commander Troy Officer with APD’s Organized Crime Unit discusses sexual assault charges against Cody Wilson. https://t.co/yF8nx0XlEt — Austin Police Dept (@Austin_Police) September 19, 2018

Wilson has been in the news frequently since 19 state attorneys general sued his company in July to prevent the free distribution of his gun-printing plans. The attorneys general cited public safety concerns for blocking the distribution.

In August, a federal judge in Seattle granted a preliminary injunction blocking the distribution of the gun blueprints until the case is resolved in court. That didn't stop Wilson, who began charging for the design files the next day, asking his customers to name their own price. He said charging for the plans got around the lawsuit because he was no longer giving them away for free.