A defense-appointed doctor testified Monday that once-prominent San Mateo child psychiatrist William Ayres is not competent to stand trial.

The San Mateo County District Attorney’s Office is retrying Ayres, 79, on charges of fondling seven male patients. A mistrial was declared in July 2009 when the jury deadlocked on all charges.

During competency proceedings Monday, neuropsychologist Dr. Amanda Gregory testified that Ayres is mentally unfit to stand trial on charges that include nine counts of lewd and lascivious acts on a child under 14.

On Tuesday, San Mateo County District Attorney Steve Wagstaffe disputed the claim, saying Gregory received $20,000 to reach that assessment and “left no possibility the defendant is competent.”

The competency proceedings were set to resume Tuesday.

Ayres allegedly molested seven teenagers during counseling sessions between 1991 and 1996.

Prosecutors believe he also molested more than 30 other victims on occasions that are now beyond the statute of limitations.

maldax@sfexaminer.com