Henan police released grisly photographs of the dungeon in which six women were held as sex slaves for up to two years and of the ex-fireman who raped, tortured and forced them into prostitution, state media reported. Adding a new twist to the scandal that has shocked the country, Central China Television (CCTV) reported on Wednesday that the four surviving women had been arrested and charged with helping 34-year-old Li Hao kill one of their two fellow prisoners who died in the dungeon. The report said prosecutors approved their arrest on Tuesday on the charge of 'causing the death of others by malicious injury'. The phone of the Luoyang Public Security Bureau's press office rang unanswered yesterday afternoon. Li Hongjiang, the bureau's deputy head, told CCTV that one of the women killed, from Sichuan, tried to fight back and was strangled by Li Hao. A second woman who struggled for freedom also died after being tortured by Li Hao and the other women, he said. 'She couldn't put up with it and together they tortured her to death,' he said, without giving details. 'She was also buried [in the basement].' One of the women was killed in the second half of last year and the other in July this year, the report said. Police found their bodies after they raided the dungeon. Some of the women were forced to help dig their own prison - a dungeon six metres underground below a cellar - where they were confined in unhygienic conditions, the report said. They were locked behind several metal gates block their escape . There were gas cylinders, electric kettles and gas cookers in the dungeon and Li Hao regularly brought noodles to feed the women, police said. They also found ventilation tubes to provide air from the outside, although the dungeon was still damp and poorly ventilated. Li Hao bought the house and cellar under his wife's name in 2008 and started digging in August 2009. He dug at night and carried away the soil in nylon bags before dawn. He brought his first victim there two months later, the report said. He lured his victims, who worked at local karaoke lounges, hair salons and massage parlours, and offered to pay them for sex before locking them up and forcing them to have sex with him in the cellar, CCTV said. The women's plight only came to light when his most recent victim, who had been confined for two months, escaped while being taken out to work as a prostitute, the report said. The woman told the police she and three other women had been detained and repeatedly raped by Li Hao and forced into performing for online pornographic shows. Li Hongjiang said some of them could have escaped earlier but did not, probably because they underwent 'severe mental torture which may have affected their judgment'. Li Hao, who was arrested early this month, faced charges of murder, rape and illegal detention, police said. He has an eight-month-old son with his wife.