The girl was arrested at about 8:30 p.m. at the Torch Lite Inn, located at 500 Riverside Ave., by an undercover cop who posed as a customer and arranged a date with her there, police said.
She was booked into Santa Cruz County Juvenile Hall on an outstanding arrest warrant issued in Sacramento County and a new charge of soliciting for prostitution, according to police.
Street crimes officers, working in conjunction with an FBI task force, found out about the girl after receiving a tip about her allegedly advertising or soliciting for prostitution on a website, along with nude photos, police said.
Investigators later found that the room the girl rented at the motel was booked by a different person. Detectives have not yet identified the woman because the motel allegedly did not ask her for identification, police said.
The motel staff received a citation for violating a municipal code that requires verified identification be taken and kept on file with the reservation, police said.
The girl was on probation in Sacramento County.
Police said prostitution has been an escalating issue in the city, especially concerning those who come from out of town to conduct their business in Santa Cruz.
The trend seems to be led by Central Valley and Sacramento area gangs who are using underage girls as prostitutes and advertising on websites for financial gain, police said.