A special agent with the Naval Criminal Investigative Service is facing trial over allegations that her romantic affair with a terror suspect damaged an FBI investigation.

Leatrice Malika De Bruhl-Daniels, 45, pleaded not guilty in October to attempting to obstruct, influence or impede justice over her relationship with 46-year-old Syrian businessman Nadal Diya.

Now, court documents reported by the Houston Chronicle reveal the steamy email Daniels traded with Diya - all while prosecutors say he was under investigation, and she had been warned not to get involved with him.

'I can't stop thinking about…you. I haven't slept for days,' one email read. 'I'm deeply attracted to you and I can't think about you like that. Don't worry, I will still fight for your visa situation as much as I can.'

Leatrice Malika De Bruhl-Daniels, 45, (above) pleaded not guilty in October to attempting to obstruct, influence or impede justice over her relationship with 46-year-old Nadal Diya

Daniels, a former FBI investigative specialist, joined NCIS eight years ago as a special agent. The agency investigates criminal activities involving the Navy and Marine Corps, and inspired the long-running CBS series.

Prosecutors say that Daniels met Diya in June 2016 while she was posted to the US consulate in Dubai, working on counter-terrorism investigations at the nearby port of Jebel Ali.

When Diya told her he was having trouble securing a U.S. visa, authorities say she used her security clearance to inquire about it and learned that he was suspected of involvement in an illegal shipment of oil equipment from the U.S. to Iran.

Officials warned Daniels in February 2017 and March 9, 2017 to break off contact with Diya, saying his entire family set off 'red flags', according to the documents.

Nevertheless, he allegedly paid for her lavish birthday party on March 29 in Dubai, hiring caterers, a DJ and special lighting. The party was attended by NCIS, State Department and Naval staff.

In May, Daniels tried to convince FBI investigators that Diya would make a good confidential informant - but they warned her to keep her distance from Diya and not to warn him he was under investigation, records show.

Daniels learned in June that Diya remained under investigation when FBI agents in Houston contacted her to ask for a full account of her relationship with him, prosecutors say. Soon after, perhaps even the same day, she allegedly warned him he was under investigation.

The NCIS agent and Diya then left on a nine-day holiday in Greece, where he gave her $1,400, she admitted.

Daniels told investigators of a transcript of text messages between herself and Diya that she had kept.

Included in the texts were a warning to Diya that it was possible 'ur phones are being monitored'.

'Whatever they hv on u is more than just suspicion so it's serious,' the transcript says, 'They know stuff and if u lie u may never see American soil!'

'I don't want to think u hv lied to me since I put my neck out there for u,' one message said.

Daniels is free on bond and awaiting trial at her mother's home in Charlottesville, Virginia.

She and her federal public defender have declined to comment about the case.

Diya is free on bond in Toronto. Prosecutors are seeking his extradition to the U.S. on charges that he used fraudulent Guatemalan and Argentinian passports in Texas and Louisiana

Trials for both are set for mid-December in Houston, but will likely be postponed.