There are now dueling criminal investigations surrounding Dak Prescott and a Texas woman ... with Dallas police launching a probe into sexual assault allegations made against the Cowboys quarterback.
As we previously reported, Dak filed a lawsuit on Monday ... claiming Victoria Shores tried to extort $100 million out of him to not go to police over an alleged encounter that occurred on Feb. 2, 2017.
Prescott and his team have maintained Prescott has never engaged in any nonconsensual acts with anyone in his life .