The 27-year-old star, who split from reality TV star Kim after just 72 days of marriage last October, had been dating the 25-year-old, whose real name is Fatmire, since meeting at a New York hotel.
The legal representatives handed over evidence proving Sinanaj demanded a large sum of money in exchange for her silence about his relationship with estranged wife Kim, reported TMZ online.
"Kris' attorneys had the meeting with officials in Minnesota and produced recorded messages from Myla which proves their point," a source said.
However the FBI would neither confirm nor deny an investigation was taking place. It had previously been reported that Humphries's lawyers were trying to get Sinanaj to sign a non-disclosure agreement.
Sinanaj reportedly has texts and other documents chronicling their relationship that could hurt Humphries's divorce court claims if they became public.