The prosecutors in the case against a Chinese woman accused of trespassing at President Trump’s Florida resort indicated they are building a national security case against her.

A federal counterintelligence prosecutor requested to file “classified information” under seal Tuesday, indicating that authorities have evidence Yujing Zhang was more than a tourist visiting Mar-a-Lago, the Miami Herald reported.

Assistant U.S. Attorney Michael Sherwin asked U.S. District Judge Roy Altman to seal evidence in the case under Section 4 of the Classified Information Procedures Act, which would allow the government to present evidence to a judge without disclosing it to the defendant in order to protect national security.

Her case is part of an FBI investigation into whether the Chinese are spying on Trump. The investigation originally centered on Li “Cindy” Yang, a South Florida business owner and Republican donor who has promoted events at Mar-a-Lago to Chinese business executives wanting access to Trump and his family, but expanded after Zhang’s arrest.

Altman ruled Tuesday that Zhang, 33, can represent herself in court after she was found to be competent after she requested to fire her public defenders and be her own lawyer.

Zhang pleaded not guilty to trespassing March 30 at the president’s Florida resort and lying to Secret Service agents about why she was at Mar-a-Lago. A judge denied her bail, saying she poses an “extreme risk of flight” if she is released from custody.

At the time of her arrest, she was carrying two Chinese passports, four cellphones, a laptop, and a device containing malware. In a search of her hotel room, prosecutors found a device that could detect hidden cameras and more than $7,500 in cash.

She told security at a checkpoint that she was there to swim. Resort employees believed she was related to a member of the club and allowed her access to the property. But when she was approached by a receptionist, she said she was there for “a United Nations Chinese American Association event later in the evening,” according to the criminal complaint, but the receptionist said there was no such event.

Assistant U.S. Attorney Rolando Garcia said in April there was “no allegation” that Zhang was involved in “any espionage.”

No charges have been brought against Zhang under the Espionage Act.