LOS ANGELES — While one Los Angeles police officer acted as a lookout in the front seat of a departmental car, a 19-year-old woman working as a drug informant was forced to perform oral sex on his partner in the back seat after being told, “You have to do what the police tell you to do,” the teenager said in a federal court filing.

Another woman, also working as a drug informant, said the same two officers each forced her to have sex with them twice after threatening her with jail time.

Two other women told eerily similar stories.

On Wednesday, prosecutors announced that veteran Officers James Nichols and Luis Valenzuela had been arrested and charged with repeatedly raping the four women over a three-year period, mostly while they were on duty.

The charges against Nichols, 44, and Valenzuela, 43, include rape under color of authority and oral copulation by force. Valenzuela also is charged with pointing a gun at one of the women.

They could face life in prison if convicted.

Attorneys representing the officers in civil litigation filed by the women did not return messages seeking comment Wednesday. The officers, who have denied all the claims in court records, were set to be arraigned on Thursday.

Prosecutors are asking that they each be held on bail of more than $3.5 million.

Los Angeles Police Chief Charlie Beck said at a news conference Wednesday that both officers have been suspended without pay since 2013. Their employment status is pending an administrative hearing that would follow their criminal case, he said.

“These two officers have disgraced themselves, they disgraced this badge, they disgraced their oaths of office,” Beck said. “It’s a violation of public trust.”

He said investigators are actively seeking other potential victims.

Prosecutors said the rapes began in December 2008 after Nichols and Valenzuela became partners in the department’s Hollywood Division. They were working as narcotics investigators.

Prosecutors say all four women assaulted had been arrested on drug-related charges at various times by the officers, and court records show at least two had been recruited by the officers to work as drug informants.

Those women have filed civil rights lawsuits against the officers. The Los Angeles City Council settled one case last year after agreeing to pay one woman $575,000, while the other case is still being litigated.

A third lawsuit is expected to be filed.

Beck said the department’s internal affairs bureau began investigating the officers after the first woman complained of being raped in 2010. In 2014, the department’s elite Robbery Homicide Division took over.

Asked why it took so long for the charges to be filed against the officers, Beck said the investigation was complicated and involved reluctant witnesses who were difficult to find.

Dennis Chang, an attorney who represents two of the women in the case, said the officers took advantage of the women’s positions and threatened them with jail time or outing them as informants.

“These women were drug users, they’re primarily arrested and in custody, in an extremely vulnerable state,” Chang said. “They were afraid.”