To keep his prostitutes from running away, Richard Jackson forced them to become addicted to heroin, court documents say, then became their only way to get a fix.

As a backup measure, the documents say, he locked them in the upstairs bedroom of a run-down house in south Detroit behind a padlocked steel gate.

They were let out to visit the hotel rooms of customers who arranged for sex via, or to walk the streets in search of customers under the watchful eye of their pimp, according to a criminal complaint filed Friday in U.S. District Court.

On Thursday, after seeing Jackson inflict a particularly bad beating on a teenage prostitute, an older prostitute worried that he would continue to abuse them, or worse.

So she unlocked the upstairs door at the house and helped the two girls escape. One is 15, the other is between 12 and 14. The FBI was still looking for the girls over the weekend, according to the U.S. attorney’s office in the eastern district of Michigan.

Once they were free, the woman dialed 911 and asked officers to come to the house to rescue the others.

“My sister’s in the basement. You’ve got to get to her. He’s going to kill her,” she told the officers, according to a police report obtained by the Detroit Free Press.

The 911 caller was taken to police headquarters, where she recounted the chilling tale of the past few months.

Jackson, 67, of Detroit was charged in federal court with sex trafficking, although a criminal complaint accuses him of a litany of other crimes, including kidnapping victims and beating them when they were defiant.

An affidavit from FBI Special Agent Taylor Debel described Jackson’s alleged methods.

“Jackson and his associates would get the ‘girls’ hooked on drugs in order to keep them at the house,” according to Detroit ABC affiliate WXYZ. “They often gave the girls heroin just long enough to have them addicted. Once addicted, Jackson and his associates began making the girls do commercial sex dates and move drugs for them.”

Sometimes, the prostitutes would “walk the track” on Livernois Avenue, a hotbed for prostitution located near three interstate highways. As the prostitutes worked, Jackson or a friend reportedly would stay nearby, but out of sight.

Jackson also posted the girls on using several phone numbers, the affidavit said. If the girls were going to a customer’s home or hotel, Jackson drove, it said. The advertisements were posted under Detroit’s escort section. One was listed under “Kitty” and told potential customers to “ask about the 2 girl specials Text or call about prices and incall info.”

Sometimes, customers would come to the house on South Electric Street for “incalls.” The two back rooms on the first floor were used for sex. The room upstairs was a de facto cell.

“Jackson took 100% of the girls’ money,” the criminal complaint says. “Each girl gave Jackson the money after each date.”

If the women refused to work or didn’t perform well as prostitutes, they were beaten, according to USA Today.

Things reached a boiling point on Nov. 7. The woman who ultimately called 911 told Jackson she didn’t want to have sex for money anymore.

Jackson broke her arm. The injury was so bad that she had to go to a hospital and needed surgery.

After the woman returned from the hospital, court documents say, Jackson broke the same arm again.

The interview with police that implicated Jackson was given after the prostitutes were examined by doctors. The woman who called 911 had a healing scar from the broken arm. Another had a knot on her head and an open wound behind her ear.

Officers obtained a search warrant and interviewed Jackson, then arrested him. He denied being involved with prostitution or drugs. His attorney could not be reached Saturday. He made his first court appearance on Friday, according to the Detroit News, and has a bond hearing scheduled for Monday.

But the investigation turned up evidence that backed up the 911 caller’s claims.

On Jackson’s cellphone, investigators saw several “text messages, discussing prices, sex acts and locations to meet” for paid sex.

They also searched the house and discovered cellphones, laptop computers, used condoms and hypodermic needles “very common with narcotic use, primarily heroin use.”

At the top of the stairs, court documents say, officers saw “a large black/metal steel gate … along with a large padlock.”

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