Jerusalem (CNN) A months-long criminal investigation of Prime Minister Benjamin Netanyahu hangs over the Israeli leader as he prepares to host President Donald Trump later this month.

Netanyahu, who has repeatedly denied any wrongdoing, has been questioned three times in two different cases in the ongoing graft probe, with another questioning likely.

In the first case, called Case 1000, Netanyahu is suspected of having received gifts from businessmen overseas, including cigars for himself and champagne for his wife, Sara. The case has focused primarily on Netanyahu's relationship with billionaire Hollywood producer Arnon Milchan.

Netanyahu has lashed out against the accusations, calling them an "attempt to overthrow the government in an undemocratic way." He has repeated what has become his mantra during the investigation: "There will be nothing because there is nothing."

Nir Hefetz, Media and Communications Director for the Netanyahu family, said, "We're talking about cigars that were given many times over the course of 17 years of friendship, so the claims that one present worth hundreds of thousands of shekels was given, or that many presents worth thousands of dollars each were given, is simply not true."

"In the course of all these years, there were no vested interests and nothing was given in return," Hefetz added. "The close friendship between the families is an unequivocal fact and cannot be denied."

Milchan's publicist Ronen Tzur has said that his client and his team are not commenting on any of the reports, whether they are "true or false and completely imaginary."

Months to go

The second case, called Case 2000, involves conversations Netanyahu had with Arnon Mozes, the owner of one of Israel's leading newspapers, Yedioth Ahronoth, which is regularly critical of the Prime Minister.

In the conversations, transcripts of which have been leaked in the Israeli media, Netanyahu allegedly discusses limiting the circulation of Yedioth Ahronot's biggest competition in favor of more favorable coverage. Both Netanyahu and Mozes have said they were not serious discussions; rather, they each claim they were trying to expose the other's lack of trustworthiness.

The investigation, which began as a preliminary examination last summer before being upgraded to a criminal investigation in January by Israeli Attorney General Avichai Mandelblit, a Netanyahu appointee, is likely to continue into the summer, a source close to Netanyahu told CNN.

Israeli Police Chief Roni Alsheikh told reporters in late January that investigators were nearing the end of their work, and that they would soon issue their advice on whether the Prime Minister should be charged.

However, no recommendation has yet been issued. If police do support an indictment, then it will be up to the Attorney General to decide whether to file charges. The source told CNN Mandelblit will likely make that decision in early fall.

Will there be an indictment?

In Netanyahu's first term as Prime Minister, in the late 1990s, facing two different graft probes, police recommended indictment, but the then Attorney General declined to file charges , citing a lack of evidence.

In the current probe, police will likely not recommend an indictment in Case 2000, the source close to Netanyahu told CNN, because no agreement was ever reached between the Prime Minister and the newspaper owner, and nothing was ever exchanged.

However, Case 1000 could see police recommending indictment, the source said. Despite that, the source close to the Prime Minister told CNN he believes the Attorney General would ultimately decide not to file charges, on the grounds that it would not be possible to prove that Milchan had gained, or had expected to gain, in any way from gifting Netanyahu the cigars and champagne.

The investigation is now being led by Liat Ben-Ari, a prosecutor with a hardline reputation, who led a corruption case against former Prime Minister Ehud Olmert . Ben-Ari, head of the Financial Crimes Division at the Tel Aviv District Attorney's Office, succeeded in getting a judge to sentence Olmert to six years in prison , though that sentence was later reduced on appeal to 18 months.

'Hard to believe'

Speaking at an event for the Israel Bar Association Tel Aviv District last week, Ben-Ari was asked about the legality of receiving gifts. The question did not mention Netanyahu by name.

"When it is about hundreds of thousands of shekels given to a public servant, I find it hard to believe that it is just a present from one friend to another ... I know how it is with me and my friends: none of us have received, and none of us have demanded, hundreds of thousands of shekels as gifts," said Ben-Ari, in what was taken as a reference to Netanyahu.

She went on: "Let's say 1,500 shekels are given from someone, with an interest, to a public servant who advances those interests, then that person should be put on trial. The person might not end up going to prison for six years, that is a question of punishment; but it is not a question of whether or not to put the person on trial in the first place."

Under Israeli law, the Prime Minister does not have to resign if he is indicted. He only needs to step down if he is convicted of a crime and if that conviction is upheld throughout the appeals process. But an indictment would put tremendous public and political pressure on Netanyahu to step down.