Tesla Inc. chief executive Elon Musk and members of the board and others will take the witness stand Tuesday in the resumption of the $2.5 billion SolarCity deal trial.

A shareholder lawsuit claims the deal was rife with conflict of interest, putting the billionaire once again under fire.

According to the shareholders, the SolarCity deal was a "bailout" of the failing company. The shareholders are demanding repayment to Tesla of the cost to acquire the solar panel manufacturer.

In a sometimes testy exchange with a plaintiffs' lawyer Monday, Musk denied there was conflict of interest, saying he had nothing to gain from the all-stock purchase because he owned shares of both companies.

"Some of your questions are really tricky and deceptive," Musk told the opposing lawyer, Randall Baron. 

"I think you're a bad human being," Musk told Baron, who was pressing him to admit his fault in helping orchestrate the SolarCity takeover.

Musk said he has "great respect" for the court, "but not for you, sir," The Associated Press reported.

Baron warned Musk the case being heard in Delaware Chancery Court was "going to be a grind."

Gesturing to a thick folder of documents prepared by Baron, Musk replied: "I can tell by the binder," BBC said.

Baron repeatedly pressed Musk about proof SolarCity had been in trouble before the Tesla takeover. But Musk conceded nothing.

At the time of the acquisition, Musk was SolarCity's biggest shareholder and its chairperson. Tesla overlooked SolarCity's failure to yield the profits Musk once promised, the investors claim.

The bitterness between Musk and the plaintiffs' attorney dates to at least 2019 and a deposition in which Musk insulted Baron and questioned his competence.

Musk, who is worth $168 billion according to Forbes, denied exerting pressure on Tesla board members, saying the deal was part of a "master plan" to manufacture affordable electric vehicles.

Wedbush Securities analyst Daniel Ives called the SolarCity purchase a "clear black eye" for Musk and Tesla, in large part because SolarCity failed to generate a profit.

Analysts said even if Musk loses the case and ends up having to pay personally for the whole transaction, $2.5 billion will not even put a dent on his fortune. 

The trial is expected to last about two weeks.