The teenager whose suspected sexual exploitation ignited a Bay Area police scandal said she told internal affairs investigators at the San Francisco Police Department that she had sex with three city officers — and that in each case she was 18, they were off-duty and they did not pay her.

The teenager, who turned 18 in August and asked to be identified by her online alias of Celeste Guap, said she had had told the San Francisco inspectors about her interaction with two of the officers. But in an interview with The Chronicle, she said she had mistakenly neglected to tell them about sex with a third officer.

Police spokesman Sgt. Michael Andraychak said in a statement that the department “has an open investigation to determine if any members have had any inappropriate contact with the victim.”

Guap, who lives in Richmond and works as a prostitute, said she had sex with 29 officers in the Bay Area, and including with three Oakland police officers and one Contra Costa County sheriff’s deputy before she turned 18. One of the three Oakland officers committed suicide in September after leaving a note that referred to Guap.

Guap said she had met the Bay Area officers either through law enforcement circles — her mother is an Oakland police dispatcher — or on the streets or through social media. A few officers paid her, she said, while others warned her about antiprostitution stings or ran the names of people she knew through confidential databases.

Several law enforcement agencies have opened investigations into whether officers should face criminal charges or workplace discipline.

Guap said two of the San Francisco officers had picked her up in Richmond for sex in their cars. She communicated with one of them after he added her to his network on Instagram, she said, and she met the other after the two “flirted” while he was in uniform on Geary Street near Union Square.

She said she had sent a message to the third officer after he added her as a friend on Facebook, and that she had spent one night at his home in Vacaville.

It’s unclear how much each San Francisco officer knew about Guap, her history or her earlier suspected exploitation at the hands of other officers.

Demian Bulwa is a San Francisco Chronicle staff writer. Email: dbulwa@sfchronicle.com Twitter: @demianbulwa

More: KGO-TV’s interview with Celeste Guap.