A Party colleague of the Civic Party member allegedly beaten up by police yesterday described him as a passionate social worker who ended a year-long journey in South America to join the Occupy movement. Sporting a beard and dressed in casual wear, Ken Tsang Kin-chiu doesn't look like a typical member of the party - a lawyer or an accountant in business attire. But "Ken is a passionate guy. He is a committed social worker with a clear goal", said fellow party member Claudia Mo Man-ching, who supported his bid for a seat in the Wan Chai District Council election of 2011. Mo recalled that during the campaign she suggested he should clean up his look and remove his single earring, of which she thought mothers in Happy Valley might not approve. "But Ken told me he could not because he needed that for his work. He just blends into the young culture," Mo said. Tsang, 39, works with young people with family issues and other problems. He lost the election. Video from yesterday seems to show Tsang pouring liquid on police officers. Mo said he may have "acted in the heat of the moment", but dismissed speculation the fluid was acid or urine. TVB yesterday aired video showing a group of plainclothes police dragging a protester away from the main crowds in Admiralty before kicking and hitting the man, later identified as Tsang. The Civic Party is demanding that police investigate whether Tsang's rights were violated. Tsang is a member of the 1,200-strong Election Committee that voted in Leung Chun-ying as Chief Executive election in 2012. But he was removed from Leung's inauguration ceremony, with then-president Hu Jintao officiating, when he shouted, "Vindicate the verdict on June 4. End one-party rule." Pan-democrats use the slogan in the candlelight vigils to mark the Tiananmen crackdown. In a Facebook post, Tsang said he returned from South America "because of the situation in Hong Kong now", adding, "I must go back and join the demonstration with all HK citizens to fight for democracy and a better future."