A trusted member of a close-knit Taiwanese community in suburban Cincinnati is accused of using chloroform to knock out the teenage daughters of his friends and then raping them, prosecutors said.
"He was the guy in the neighborhood who offered to walk your dog while you were on vacation, to watch your house," prosecutor Joseph Deters said of Wu Chien-tai. "He had access to all of them through their garage codes."
A 17-count indictment released on Wednesday said Wu, 50, had been an active member of the Taiwanese community.
"He befriended them and gained their trust," Deters said.
He said Wu learned during weekly poker games when teenage girls might be home alone and later went into the homes, where the rapes were committed.
He is charged with rape, attempted rape, aggravated burglary, felonious assault, gross sexual imposition and illegal use of a minor in nudity-oriented material.
Some victims did not remember the rapes -- they had been reclothed and there were no signs of forced entry into the house -- and may have thought they had dreamed an attack, Deters said.
Wu, a computer specialist, is charged with three attacks involving girls 15 to 17 years old.
"We believe there is a good chance there are other victims out there," Deters said. "We're asking people who gave Dr. Wu their garage codes to talk to their teenage daughters."
Wu, who has a doctorate in computer science, was arrested on July 24 after an alleged attack the previous week in which the victim apparently was partly conscious and identified him.
Authorities obtained search warrants for a sample of Wu's DNA and recovered a stun gun and a bottle of chloroform in his home, Deters said.
Wu was arraigned the following day and remained in custody on Wednesday in the Hamilton County jail under a US$1 million bond, according to court records. His attorney, James Kolenich, did not immediately return a call seeking comment.
In the last attack, on July 18, a 16-year-old girl had returned home after dropping off her brother at a sports practice when a man wearing a mask shocked her with a stun gun and placed a rag soaked with chloroform over her face, Deters said.