Prosecutors in California announced plans on Tuesday to drop all charges against a former Newport Beach doctor and reality TV personality who was accused of drugging and sexually assaulting seven women with his girlfriend.

The Orange County District Attorney’s Office said in a statement that an exhaustive, monthslong review determined there was “no provable evidence” that the former doctor, Grant Robicheaux, 39, or his girlfriend, Cerissa Riley, 33, had “committed any sexual offense.”

“My sworn duty as the elected district attorney is not to secure convictions,” District Attorney Todd Spitzer said in the statement. “My sworn duty is to pursue justice and ensure that the rights of victims and defendants are protected.”

Mr. Spitzer said his predecessor, former District Attorney Tony Rackauckas, and Mr. Rackauckas’s chief of staff had “manufactured this case and repeatedly misstated the evidence.”