A physician who rocked a UC Irvine fertility clinic 15 years ago when he and a partner switched the frozen embryos of dozens of unsuspecting women, has been taken into custody by Mexican authorities, officials said Monday. Ricardo Asch, MD, one of two fertility doctors who fled prosecution as the scandal unfolded, was arrested in Mexico City on Nov. 3, said Thom Mrozek, spokesman for the U.S. attorney's office in Los Angeles. He remains in custody as U.S. prosecutors seek to extradite him to Southern California to face federal mail fraud and tax evasion charges. It's not clear how and precisely where Mexican authorities caught up with the doctor, who has been living and practicing medicine in Buenos Aires. U.S. officials have for years listed him as a wanted fugitive in postings shared with the international law enforcement community, he said.