Wu said at the time of his death Yu was emaciated, with bruises on his arms and thighs, dark welts on his buttocks and scrapes on his feet and shins. While that appeared to indicate that he was starved and beaten, the indictment made no mention of other forms of torture besides dunking.
It wasn't clear when the case would go to trial, and a man at the prosecutor's office in the Zhejiang city of Quzhou, where the indictment was issued, said he had no information about the case and refused to transfer the call to other departments. The man refused to give his name, as is common practice among Chinese bureaucrats.
Wu's Shanghai-based lawyer, Wu Pengbin, did not answer calls Thursday.
Well-known Beijing human rights lawyer Pu Zhiqiang, who has advised on the case, said there was little for Wu's legal team to do but watch the case proceed. He said Yu's death was not an isolated incident, but rather part of an institutionalized culture of torture within the party investigation system.
"The accused believe that they were performing their duties, and as far as I know torture is widely used in interrogation by party disciplinary officials across the country," Pu said. "They had to have authorization from their supervisors for what they did, and it is not fair for only them to get blamed."
Yu's death has drawn attention to the party's feared system of internal investigation under which suspects disappear into detention for weeks or months with little or no notice given to their families.
Defenders of the system say it allows investigators to prevent powerful officials from using their influence to block legal action against them.
Trained as an engineer, Yu did not seem to have that kind of power. A party member since 1998, he had been a rising figure in the state-owned Wenzhou Industry Investment Group and had been seconded to the Cabinet agency in Beijing that oversees China's biggest state-owned companies.
He was picked up by investigators upon arriving home from Beijing on March 1. Wu was never given formal notice of his detention, but learned from private sources that he was suspected of being a middleman in a corrupt land deal that eventually fell through.