As she explains in her Author's Note, Leila Mottley based Nightcrawling loosely on real events involving a teenage sex worker who was sexually exploited for months by members of the Oakland Police Department. The girl is known as Celeste Guap in court documents. According to her, she began "dating" Officer Brendan O'Brien in February of 2015, when she was 17, after running to him for help on East Oakland's International Boulevard when she was being threatened by a pimp.

Her relationship with Officer O'Brien led to Guap having sex with multiple other members of the Oakland Police Department, as well as officers from other jurisdictions, often in exchange for information about prostitution stings. As the East Bay Express (who broke many details of this story as it unfolded) explains, "[Guap's] interactions with officers as a minor fit the legal definition of human trafficking." Brendan O'Brien died by suicide and confessed to his involvement with Guap in a note, naming other officers ...