Story highlights Police: A man created underground rooms and held women captive for 2 years

They were forced into prostitution and to take part in porn videos, state media reports

2 were killed; police acted after getting a tip from a relative of a runaway "sex slave"

A police chief apologizes for the department's failure to rescue the women sooner

A Chinese police official apologized Saturday for his department's handling of a case in which a man allegedly killed two of six women he had held captive in his underground lair, where they were raped, forced into prostitution and featured in porn videos, state-run media reports.

Li Hao, a 34-year-old who had worked for the technological supervision bureau in the city of Luoyang, is currently in custody. But not before, authorities claim, he engineered an involved scheme to hold young women as "sex slaves," according to state-run news agency Xinhua.

The married father of one son admitted to digging two underground rooms in the basement of a residential compound that he'd bought two years ago. His intent, authorities said, was to make money running pornographic businesses, including uploading videos to the Internet.

The women were held two to 21 months, during which time Li forced them to perform sex on camera or have sex with others for money, according to police cited in the Xinhua report.

Police didn't act and raid Li's home, until September 3 after one of the supposed "sex slaves" escaped and one of her relatives talked with police.

On Saturday, Guo Congbin -- who directs the public security bureau in Luoyang, which is in Henan province -- said the lag time between when Li began abducting the women and police discovered him indicates that community patrols were ineffective and police had lost their sense of responsibility.

He noted four police officers have been suspended; entertainment venues, Internet cafes, beauty parlors, saunas and the like are being more closely examined; and an "online cleansing" effort is targeting porn websites.

"I beg the people of Luoyang to give us another chance," Guo said. "We will show you the results of our actions."

The Southern Metropolis Daily, a popular, relatively independent tabloid that was the first to report the story, claimed that the two women killed were both nightclub attendants and had been dead for months by the time police found their bodies three weeks ago. Authorities did not confirm this assertion to Xinhua.

They had been tortured and, eventually, killed after trying to fight back, police said.

The four surviving women have been detained for "alleged criminal involvement," with the Metropolis Daily reporting they may have helped Li kill the other two while trying to survive.