When Cheng Zhang finally went to police a week after he said his wife and stepdaughter had been kidnapped, he told a bizarre story about being knocked out with a type of mist at his apartment door, then waking up to find blood on his carpet. The 42-year-old Uber driver said a note, apparently left by two strangers of Chinese descent he remembers seeing at his door, and several others later slipped under his door, told him to behave normally if he wanted to see 34-year-old Amber Aiaz and 12-year-old Melissa Fu again. He said that was why he posed as his wife on WeChat and told his stepdaughter's school she was home sick. This all sounded rather suspicious to detectives in Irvine, Calif., per the Los Angeles Times. But a year and a half later, they've been unable to find any discrepancy in Zhang's story. Indeed, "we have exhausted every lead that we have to try to tie him to this disappearance," says Police Det. Haldor Larum.
The FBI is aware of a mist capable of knocking a person out, used in sophisticated kidnappings. And it was Zhang who pointed out the blood spots around his apartment, which he'd apparently concealed at the kidnappers' direction. Police say he's been completely cooperative and hasn't wavered through 40 hours of interviews. He also passed a polygraph test. The likelihood is that Aiaz and Melissa, now on the FBI's Most Wanted Kidnappings and Missing Persons list, are dead, per the Times. Melissa hasn't contacted her grandmother, whom she talked to every day. Aiaz—or Mei Yi Wu, per NBC News—hasn't touched her bank accounts in the US or in her native China. One theory is that Aiaz was targeted for money; police say she claimed to be a millionaire but was basically penniless. Zhang suspects organized crime. A $10,000 reward is offered in the case. (Read more kidnapping stories.)