A former FBI interpreter reportedly married a key ISIS operative she had been assigned to investigate.

Daniela Greene, 38, travelled to Syria where she was wed to German national Denis Cuspert, who was a rapper known as Deso Dog in his homeland, before changing his name to Abu Talha al-Almani in Syria.

Cuspert has been featured in videos for ISIS holding severed human heads, CNN reported.

Few weeks after her marriage, Greene realized she had made a mistake and fled back to the US, turned herself in and agreed to cooperate with authorities.

Greene used online tools like Skype to get close to Cuspert before she lied to the FBI about where she was going and warned her new husband he was under investigation, according to federal court records.

She was accordingly sentenced to two years in prison, though prosecutors described what she committed as deserving of “severe punishment.”

After Greene finished cooperating with authorities, prosecutors asked the judge to unseal portions of the court file, including Greene’s identity.

“Unsealing these documents will allow appropriate public access to and knowledge of the circumstances of this case,” prosecutors stated.

“It’s a stunning embarrassment for the FBI, no doubt about it,” John Kirby, a former State Department official stated.

Greene’s attorney, Shawn Moore, said she was “genuinely remorseful.”

“She was just a well-meaning person that got up in something way over her head,” Moore said to CNN.