Updated

Golfer Phil Mickelson says he won't be called as a witness in a federal insider trading criminal trial.

Federal prosecutors and defense attorneys have both described Mickelson as pivotal figure in the case against gambler William "Billy" Walters. Mickelson does not face criminal charges, but agreed to repay nearly $1 million he made on a 2012 stock trade.

The case is on trial in New York. Mickelson is playing this week at the Dell Technologies Match Play where he won his first-round match Wednesday. Mickelson said he's not thinking about the trial and said he's not a part of the case.

Mickelson said "I won't be called" as a witness, but didn't say how he knows that.

Although prosecutors and defense attorneys haven't said Mickelson would be called to testify, the judge has hinted it could be possible.