Samuel Chu Muk-man, son of Occupy Central cofounder and Baptist pastor Chu Yiu-ming, has quit as managing director of the Hong Kong Democracy Council in the United States.
His resignation comes amid reports of his involvement in efforts to persuade the US government to sanction SAR officials and some prominent figures.
Chu went online on Monday night to announce his resignation and to say council board members Annie Wilcox Boyajian and Victoria Hui Tin-bor were stepping down too.
"We are honored to have served Hong Kong through the HKDC over the past two years and help create a powerful voice for Hong Kong," wrote Samuel Chu.
An arrest warrant for him was issued in the SAR last July for allegedly breaching the national security law.
The Hong Kong Democracy Council also said Chu resigned, but it did not offer a reason.
Council board president Anna Yeung-cheung said Chu was "instrumental in building the HKDC from scratch" and had, from September 2019, "worked tirelessly to amplify the voice of Hongkongers in the United States."
Besides a necessary restructuring of its leadership team, Yeung added, the council will strengthen ties with US policymakers and the global Hong Kong activist community.
The Washington-based council sells itself as a nonpartisan, nonprofit organization dedicated to promoting democracy and human rights in Hong Kong.
It lobbied for the passage of the Hong Kong Human Rights and Democracy Act, enacted in November 2019, and the Hong Kong Autonomy Act that mandates penalties against Hong Kong and mainland officials.
The council is one of seven entities on which Beijing imposed sanctions last month - a response to a US advisory on deteriorating freedoms in Hong Kong.
Sing Tao Daily, The Standard's sister publication, reported that Andy Li Yu-hin, one of 12 people arrested in a boat off Guangdong when bidding to reach Taiwan, handed a list of 144 names to Chu in December 2019.
Chu then passed on the list to two US senators, Rick Scott and Ted Cruz, and UK Conservative Party activist Luke de Pulford.
The list included Hong Kong politicians and officials recommended for sanctions. It allegedly went through Next Digital founder Jimmy Lai Chee-ying.
The report also said that among those named were TVB news chief Keith Yuen Chi-wai, Executive Council member Tommy Cheung Yu-yan, and John Tse Chun-chung, a former chief superintendent who spearheaded the police force's press conferences during the unrest two years ago.
In the high court on Thursday, Li and Chan Tsz-wah, 29, admitted to colluding with Lai and others to ask foreign forces to impose sanctions on Hong Kong and the mainland.
Prosecutors alleged that Chan acted as an agent for Lai and adviser Mark Simon by conveying the duo's instructions to Li and Finn Lau Cho-dik, core members of Stand With Hong Kong, an organization set up in August 2019 whose goal was to appeal to different countries to impose sanctions against the mainland and the SAR.