A man who became an advocate for victims of the 2008 tainted milk scandal is on trial in Beijing. Zhao Linhai pleaded not guilty on Tuesday to charges of, "provoking an incident," according to his lawyer.

Zhao had organized a support group for parents of children who got sick from drinking milk tainted with the chemical melamine. Chinese state media reported that more than 300,000 kids got sick and at least six died after drinking the tainted milk. Zhao’s own son was affected and had a kidney stone.

Zhao had rallied supporters to call for greater accountability in the scandal—and for compensation for the victims. On November 13, 2009, Beijing police took Zhao from his home. His wife and kids haven’t seen him since.

Zhao’s wife was not allowed inside the courtroom and stood outside with a dozen supporters.

The trial lasted six hours. Zhao’s lawyer expects a verdict within two weeks.