When reports of violence gripped Hong Kong on the evening of June 12 as the police sought to break up the crowds of anti-extradition protestors with tear gas, rubber bullets and water cannons, 38-year-old Ricky Chui Yat Sing was still working at the Hong Kong police headquarters.

Upon returning home the next morning at 10am after working overnight, he couldn’t sleep at all. He decided to quit the police force, join the protestors and face up to his own ex-colleagues.

“I couldn’t be serving the police force anymore,” the 38-year-old born and bred Hongkonger told Vice News. “I want my daughter to grow up and live in a safer and freer place. I don’t want Hong Kong to become the mainland.”

Activists are demanding that the government give a full accounting of the police brutality that was unleashed on the city and set up an independent investiation committee on the use of police force in the protests.