Investigators are in possession of correspondence between the prime minister's wife, Sara Netanyahu, and the wife of a business tycoon that appear to implicate her in the burgeoning Bezeq corruption scandal, Channel 10 News reported Thursday.
The reports said Netanyahu tried to get favourable coverage on the Walla! news site owned by Shaul Elovitch, the controlling shareholder of Israeli telecommunications giant Bezeq, in exchange for policies benefitting Bezeq.
Police have now questioned the premier eight times since the beginning of 2017, and last month said there was sufficient evidence to charge him with graft, fraud and breach of trust in two other cases.
Netanyahu has repeatedly denied wrongdoing in both cases and has questioned the integrity of high-ranking officers handling the investigations, calling the probes a politically motivated "witch hunt".
The company has denied wrongdoing.
A representative for Elovitch had no immediate comment and Hefetz's lawyer did not respond to a request for comment.
A final case, dubbed 3000, is being investigated separately and has involved Netanyahu allies, but the prime minister has not been named as a suspect.
Meanwhile, about 70 protesters gathered outside Netanyahu's residence, demanding his resignation. "Let our people go free from all the corruption surrounding the administration and the head of it", Shimrit Orr, a 72-year-old writer from Tel Aviv, said.
Some drivers touted their horns in support as they drove by.
He's stated that he will seek a fifth term in a nationwide election due in late 2019.
In Case 1000, police say Netanyahu received gifts worth 1 million shekels ($280 million) from overseas businessmen. In return, police say Mr Netanyahu operated on Mr Milchan's behalf on United States visa matters, legislated a tax break and connected him with an Indian businessman.
The second case relates to an alleged deal for favorable coverage with Arnon Mozes, publisher of prominent Hebrew-language daily Yedioth Ahronoth.
So far, partners in Netanyahu's governing coalition have stood by him, saying they were awaiting the attorney-general's next moves.
However, surveys also show that about half of Israelis believe the police over Netanyahu and think he should step down.
If investigators discover a promise for favorable coverage, Sarah Netanyahu could be charged.