After Nissan’s board voted unanimously to oust Carlos Ghosn as chairman during an emergency meeting at its headquarters in Yokohama, Japan, some industry observers are questioning exactly what the case really involves.

The board of Nissan’s French alliance partner Renault has notably chosen not to oust Ghosn as its own CEO, while waiting for clear evidence. Several sources told NBC News they questioned why Ghosn was even arrested.

The 64-year-old executive was arrested on Monday in Japan and accused of under-reporting his income by almost $45 million and misusing company assets. The Brazilian-born executive could remain in detention in Tokyo for as much as 10 more days before prosecutors decide whether to bring a formal indictment.

This may involve a “lethal brew of politics and international business intrigue,” said Joe Phillippi of AutoTrends Consulting. While he cautioned that it might be “a stretch,” he quickly added that it is “not out of the realm of possibility” that the accusations leveled against Ghosn were motivated by an internal corporate dispute.

That was echoed in a half-dozen other conversations with those inside or close to Nissan, with sources echoing the fact that there had been a sharp falling out between Ghosn and Saikawa, who replaced Ghosn as Nissan CEO last year.

“Companies typically may give you a slap on the hand” when you play a little loose with the use of things like a corporate jet or charge things to your expense account that aren’t justified, said one Nissan veteran, “but they don’t have their chairman arrested and put in jail.”

If the case is not rock-solid, some industry watchers forecast Saikawa could wind up being forced out himself. The Nissan CEO seemed clearly confident in the charges leveled against Ghosn during a news conference at corporate headquarters on Monday, declaring, "Beyond being sorry I feel great disappointment, frustration, despair, indignation and resentment."

But he also may have signaled a personal element to the case by suggesting that Ghosn had gained too much power and may have stayed in his position too long.

Ghosn joined Renault in 1996, brought on board to fix the French company's finances. He put it in the black in barely a year, earning the nickname, “Le Cost Killer.” Ghosn was then sent to Japan in 1999, after Renault purchased a 38.6 percent stake in Nissan, to implement a massive turnaround plan. Initially named chief operating officer, Ghosn was soon elevated to CEO after the Japanese carmaker began turning a profit and had slashed its crippling debt. He was subsequently named chief executive at Renault, and held the same position at the umbrella organization now known as the Renault-Nissan-Mitsubishi Alliance.

In his various posts, Ghosn not only had to deal with running a far-flung business empire but also with the political pressures associated with the Franco-Japanese group. In 2017, the French government trimmed back its holdings in Renault – partly due to maneuvering by Ghosn – to 15 percent. But it still holds significant sway and has been pressing to further consolidate the Paris-based automaker and Nissan, something that French Finance Minister Bruno Le Maire re-emphasized this week.

If anything, Nissan has been pushing for a bit more independence under Saikawa. But Reuters quoted company sources as suggesting “There is a feeling of crisis at the (Japanese) Ministry of Economy, Trade and Industry that at this rate Nissan and Mitsubishi will be seized by the French government.”

Some observers warn things could go in the other direction for the alliance if the French press too hard – or the Japanese maneuver too aggressively to prevent a takeover.

Earlier this week, Mitsubishi CEO Osamu Masuko said the very alliance that Ghosn strung together is in jeopardy. “I don’t think there is anyone else on Earth like Ghosn who could run Renault, Nissan and Mitsubishi,” he said.

Those on both the French and Japanese side of the alliance have been trying to downplay such concerns. Saikawa expressed his desire to retain what has been a massively positive relationship that last year nudged past Volkswagen to become the world’s best-selling automotive group by unit volume.

While those on the Renault side continued to demand evidence of Ghosn’s alleged crimes, the company also issued a statement stressing its "dedication to the defense of Renault's interest in the alliance.

"But there is no doubt that the loss of Ghosn will pose a major challenge. He is 'the glue that holds Renault and Nissan together,'" said Max Warburton, an analyst at Bernstein. "It is hard not to conclude that there may be a gulf opening up between Renault and Nissan."

Should further questions be raised about the justification for Nissan’s charges and Ghosn’s arrest, several sources warned, that gulf could turn into an ocean. And it could put a new, unflattering spotlight on Saikawa himself.