A California man is suspected in a string of sex worker slayings in Mexico, the top prosecutor in Baja California said Friday.

Federal authorities arrested Bryant Rivera, 30, on Thursday in Downey, a city in Los Angeles County, at the request by Mexican authorities, according to court documents and U.S. officials.

He was placed in federal custody pending a pretrial detention hearing on Monday in Los Angeles, said Thom Mrozek, spokesperson for the U.S. Attorney’s Office for the Central District of California.

Federal officials said they expected Mexican prosecutors to formally request extradition.