BUENOS AIRES (Reuters) - Russian President Vladimir Putin walked up to Saudi Arabia’s Crown Prince Mohammed bin Salman at a summit of G20 world leaders, high-fived him and then shook his hand heartily. Moments earlier the prince had been pictured on the far edge of the traditional “family portrait” photograph, ignored by other leaders.

Saudi Arabia's Crown Prince Mohammed bin Salman greets Russia's President Vladimir Putin during the opening of the G20 leaders summit in Buenos Aires, Argentina November 30, 2018 in this picture taken from video. Reuters TV Summit Pool via REUTERS

The two moments captured the dilemma facing world leaders at the Group of 20 summit in Buenos Aires this weekend: How to deal with the crown prince, who is dogged by controversy over the murder of a Saudi journalist but is also de facto leader of a rich, oil-producing kingdom that is a major global investor.

To be sure Putin’s exuberant greeting of the prince was seen as over the top and promptly went viral. But, while leaders appeared to ignore Prince Mohammed on stage during the “family photo,” many went on to have closed-door bilateral meetings with him during the two-day summit.

The Saudi government media office, in a statement responding to an earlier Reuters story about Prince Mohammed being sidelined in the photo, said he was standing “in the same proximity to the center of the group” as in a similar photo at the G20 summit in China two years ago.

The crown prince, facing a global outcry over the killing of journalist Jamal Khashoggi in the Saudi consulate in Istanbul two months ago, had conversations with at least 12 world leaders.

Three of them, Canadian Prime Minister Justin Trudeau, British Prime Minister Theresa May and French President Emmanuel Macron, said publicly they had pressed Prince Mohammed for a full investigation into the murder.

Saudi Arabia has said the prince had no prior knowledge of Khashoggi’s murder. Turkish President Tayyip Erdogan has said the killing was ordered by the highest level of Saudi leadership but probably not King Salman, putting the spotlight instead on the 33-year-old crown prince.

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Trudeau said he had a frank conversation with the prince at a leaders’ dinner on Friday, telling him there was “a need for better answers on the killing of Khashoggi.” May said she called for a full, credible and transparent investigation, while Macron insisted the crown prince allow international investigators to take part in any inquiry.

U.S. President Donald Trump, who has defended U.S. ties with Saudi Arabia, “exchanged pleasantries” with the crown prince, the White House said. Trump has said it may never be known if Prince Mohammed ordered the killing or not. Sources say the CIA believes the crown prince ordered the killing.

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The crown prince also discussed investments and economic partnerships with Indian Prime Minister Narendra Modi and Chinese President Xi Jinping. Readouts of those meetings did not say whether Xi and Modi had confronted the prince over the Khashoggi case.

“China firmly supports Saudi Arabia in its drive for economic diversification and social reform, and will continue to stick together with Saudi Arabia on issues involving their core interests,” Xi said, according to China’s official Xinhua news agency.

Modi and Prince Mohammed discussed scaling up investments in India’s tech, farm and energy sectors, according to an Indian official and the Saudi news agency (SPA).

Before the start of the gathering, Argentinian President Mauricio Macri had said it was possible that the accusations against the crown prince could be discussed when the leaders convened.

In the end, they were not.

Days before the summit, Human Rights Watch called on Argentina to use a war crimes clause in its constitution to investigate any involvement by the crown prince in possible crimes against humanity in Yemen, where a Saudi-led military campaign is under way, and Khashoggi’s murder.

The federal prosecutor’s office assigned to review the case had not announced whether a formal investigation would be opened by the close of the summit on Saturday.