Jerusalem (CNN) Israeli police said Tuesday there was "sufficient evidence" to indict Prime Minister Benjamin Netanyahu on criminal charges in two corruption cases.

Here's what you need to know about the scandal engulfing the Israeli leader.

Why is Netanyahu being investigated?

Netanyahu is a suspect in two separate criminal investigations, known as Case 1000 and Case 2000. The cases involve allegations of receiving bribes, fraud, and breach of trust, according to police.

In Case 1000, Netanyahu is suspected of having received gifts from businessmen overseas, including cigars for himself.

The case has focused primarily on Netanyahu's relationship with Israeli billionaire and Hollywood producer Arnon Milchan, though the investigation has expanded to include other wealthy businessmen with ties to Netanyahu.

Nir Hefetz, who was once Media and Communications Director for the Netanyahu family, downplayed the seriousness of the investigation last summer. "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."

"The close friendship between the families is an unequivocal fact and cannot be denied," Hefetz added.

Milchan also denied any wrongdoing. "Milchan was asked to complete his testimony, and accordingly gave full testimony as he has done in the past, and acted in complete innocence for the good of the country in his eyes, while making sure he complies with the law," his lawyer said in September.

In Case 2000, police have investigated conversations Netanyahu had with Arnon "Noni" 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 Ahronoth's major competitor -- the Sheldon Adelson-owned Israel Hayom, a right-wing newspaper seen as favoring Netanyahu -- in exchange for more favorable coverage.

Both Netanyahu and Mozes have said these were not serious discussions; rather, they each claim they were trying to expose the other's lack of trustworthiness.

Netanyahu has repeatedly proclaimed his innocence, insisting that investigators will find he did nothing wrong.

In a televised statement on Tuesday, Netanyahu said that the police recommendations "will end in nothing" and that the allegations against him "have no basis."

Police will now pass the evidence to the Attorney General, who will make a decision on whether or not to indict Netanyahu. That decision is not expected imminently.

When did the investigations begin?

Before rising to the level of criminal investigations, these inquiries began as examinations in July 2016. Six months later, investigators uncovered evidence to warrant an official investigation, according to a statement from Attorney General Avichai Mandelblit.

Netanyahu has met with investigators and been questioned 7 times now, most recently on December 15, 2017.

Police revealed the suspicion of fraud, receiving bribes, and breach of trust in August 2017.

When did the investigations get serious?

Any police investigation of a Prime Minister is a serious matter, but the investigation reached a new level in early August when Netanyahu's former chief of staff, Ari Harow, turned state's witness , agreeing to testify against his old boss.

The American-born Harow served under the Prime Minister when he was elected to his second term in 2009.

As part of the deal, Harow agreed to plead guilty of committing fraud and breach of trust in an entirely separate case. In exchange, prosecutors will request that Harow be handed six months of community service and a fine of 700,000 shekels (around $200,000) instead of a jail term, which such offenses usually attract.

Is he the only Netanyahu being investigated?

Benjamin Netanyahu arrives with his wife Sara for the United Nations General Assembly meeting in New York in September 2017.

Netanyahu's wife is also under investigation, but in a completely separate case.

In September, Attorney General Avichai Mandelblit told Sara Netanyahu that he is considering an indictment on fraud and breach of trust offenses.

Mandelblit had been weighing a series of police investigations into Sara Netanyahu, but said that he was still pursuing only one of the cases against her - referred to in the statement as the "Meals Ordering Affair."

The allegation in this case is that between September 2010 and March 2013, Sara Netanyahu, along with a senior official at the Prime Minister's office claimed 359,000 shekels (about $100,000) in catering expenses from restaurants and hired chefs, even though there were cooks and chefs employed at the Prime Minister's official residence.

Submitting such expense claims is only permissible, according to the rules governing the Israeli Prime Minister, in the absence of official cooks at the residence. Sara Netanyahu had a hearing in front of the Attorney General before he made his final decision.

Sara Netanyahu has denied the allegations against her, pointing to an array of other investigations that were closed without indictment.

"The only thing the AG is still considering is the issue of food platters ordered for the Prime Minister's Office. That too is subject to a hearing and will be refuted completely," she said in September.

Are the Netanyahu probes the only ones facing the government?

No. Police are also investigating a case known as Case 3000, which involves the multimillion dollar purchase of German submarines and attack boats.

The procurements were made during Netanyahu's premiership, though the Attorney General has explicitly said that Netanyahu is not a target of the investigation.

Many in Netanyahu's inner circle have been questioned, and some have been named as suspects in the ongoing investigation.

This month, Israel's Police Chief, Roni Alsheich, said for the first time that Netanyahu will give testimony as part of Case 3000.

There are other members of Netanyahu's Likud party that are under investigation, but those cases are unrelated to Case 1000, 2000, or 3000.

Is Netanyahu worried?

Netanyahu has repeatedly denied any wrongdoing , rallying his supporters to back him. Outwardly, he has displayed an abundance of confidence that he will be cleared.

And why not? During Netanyahu's first term in the late 1990s, police recommended indicting him in two separate cases. Both times, the Attorney General decided against filing an indictment, ending the investigations against the Prime Minister. Netanyahu has predicted the same will happen again.

Under Israeli law, Netanyahu doesn't have to resign if police recommend an indictment. In fact, he only has to resign if he is convicted and if that conviction is upheld through the appeals process to the High Court, a process that could theoretically take years.

It's worth noting that other Prime Ministers have also had cases closed against them without charges being filed, including Ariel Sharon and Ehud Barak.

But, more so than anyone else, Netanyahu is aware of the unforgiving reality of Israel's political system. He has the backing right now of all of the parties in his coalition because he has won four elections and is a proven winner in domestic Israeli politics. He is an asset, especially to a right-wing government.

The moment he becomes a liability - either to his own party or to other political parties in his coalition - Netanyahu is in trouble.

In 2008, then-Prime Minister Ehud Olmert was pressured to resign by Ehud Barak, his Defense Minister and main coalition partner. Olmert was under investigation for suspected corruption and Barak believed he had become too much of a political liability.

It is also worth recalling that Netanyahu's government is firmly of the right-wing. If any of the parties in the coalition took down the government, it would likely mean shifting away from a right-wing ideology. That might not play well with those parties' conservative voter base.

Should he be worried?

Israel has not shied away from investigating and prosecuting its leaders and senior politicians.

Olmert served 16 months in prison after being convicted of taking cash from an American businessman, and receiving bribes for a housing project while he was the Mayor of Jerusalem.

Former President Moshe Katsav was convicted of rape and sexual harassment, serving five years in prison.

Aryeh Deri, the leader of the ultra-Orthodox Shas party, was convicted of taking bribes while he was the Interior Minister. He spent nearly two years in prison. He returned to politics about a decade after his release, and is once again serving as Interior Minister.

In short, if Netanyahu expects his position as Prime Minister to shield him from the investigations, history says he is mistaken.

Dismissing the chance that he would step down if police recommend an indictment, Netanyahu said, "half the recommendations from police end in nothing."