A federal magistrate judge has refused to release a California woman accused of spying for China, rejecting a bond package that included more than $700,000 in home equity and ruling that she remains too much of a flight risk to go free while her case proceeds.

Wanying "Heather" Zhang, 34, of Irvine, was arrested Oct. 4 at Los Angeles International Airport as she tried to board a flight to China. She's charged with acting as an unregistered agent of a foreign government, a federal count that doesn't require prosecutors to prove classic espionage — only that she acted at the direction of a foreign power without registering with the Justice Department.

According to the FBI's account, cited by Fox News, Zhang surveilled the son of Taiwan's president and his family in Seattle last year, taking photos and video and passing license-plate information to Chinese officials. Prosecutors allege she was paid through an unregistered cryptocurrency exchange business, with the money ultimately landing in a Chinese bank account.

A rejected bond, and a family tie to Beijing

Zhang's defense team offered U.S. Magistrate Judge Steve Kim a release package built around her Irvine home — more than $700,000 in equity — plus roughly $120,000 in additional financial guarantees from her husband, his sister, his father and a family friend. Her lawyers argued the government's entire case centers on a single day of alleged surveillance and that her U.S. citizenship and family ties in California showed she wasn't going anywhere.

The judge wasn't persuaded. According to Taiwan News, Kim sided with prosecutors, who told the court Zhang's parents and siblings all live in China and that her brother has a documented history of working with the Chinese government — factors the judge cited in ruling she poses a genuine flight risk and ordering her held without bond pending trial.

HER FAMILY IS IN CHINA. HER BROTHER HAS WORKED FOR BEIJING. A JUDGE SAID THAT'S ENOUGH TO KEEP HER LOCKED UP

Zhang is a naturalized U.S. citizen, which her attorneys have pointed to repeatedly as evidence she poses no danger of fleeing. Prosecutors see it differently, arguing that citizenship doesn't erase the family and financial ties to China that, in their telling, give her both the motive and the means to disappear if released.

The case is one of a steady stream of unregistered-foreign-agent prosecutions U.S. authorities have brought in recent years targeting alleged Chinese surveillance of dissidents, officials and, in this case, relatives of a sitting foreign head of state on American soil. Taiwan's government has not issued extensive public comment on the specific allegations against Zhang, and it's not clear whether her targets were aware they were being watched.

Zhang remains in federal custody as the case moves toward further pretrial proceedings. Her attorneys have not said whether they'll appeal the detention ruling, and no trial date has been set.