REDWOOD CITY, Calif. --   A former San Mateo child psychiatrist accused of molesting several
young patients took the stand in his own defense in San Mateo County Superior
Court Thursday and discussed the physical examinations he performed on his
patients that led to the molestation accusations.

   William Ayres, 77, appeared calm as he began testifying at 1:30
p.m. Gray-haired, bearded and soft-spoken, he answered questions from his
defense attorney Doron Weinberg about the physical examinations he performed
on patients in the more than 40 years he practiced medicine until his
retirement in 2005.

   Ayres is charged with 10 counts of lewd and lascivious conduct on
a child under 14 for allegedly molesting six boys between ages 9 and 13 from
1988 to 1996.

   The bulk of the accusations against Ayres deal with physical
examinations the doctor conducted on his patients, which Wednesday Ayres
described as "useful" when treating patients but which prosecutor Melissa
McKowan said were "not legitimate."

   Ayres testified that he was "very hands-on with patients" by
arranging hospital visits if they needed them, visiting the patients at home
in an emergency and going to the patients' schools.

   He said he was not reluctant to conduct physical examinations on
his patients as well, sometimes in order to get to know them at the beginning
of their treatment and other times as a way of ensuring their health.

   "I think physical exams develop a kind of trust, and (the
patients) start talking," Ayres said. Or "if they had an established illness,
then I would do a physical exam to get to know them.

   "Certainly when you do a complete physical exam, you listen to the
heart and lungs and check the belly, and in the case of a boy you should
check ... the testicles and scrotum," he said.

   When asked whether all his patients agreed to the physical exam,
Ayres said he never heard them say no, and sometimes it was hard to gauge
their responses.

   Ayres recognized the physical examinations may have been stressful
for the patients and said he never conducted one without the patient's
consent.

   "I've never forced a child or intimidated a child," he said. "I
never ordered a child to consent to a physical exam. Some children were very
uncommunicative.

   "It's meant to be positive and lead to more understanding of the
child," Ayres said.

   Sometimes, he said, he found what appeared to be self-inflicted
cuts or track marks from drug use on his patients' bodies.

   One man, Greg H., who was a patient of Ayres in the 1980s and
whose claims fall outside the statute of limitations, told jurors that on his
first visit Ayres asked him to remove his shirt and proceeded to check for
track marks on his arms, even though Greg H. said there was no mention of a
possible drug problem.

   Greg H. said the doctor touched his genitals on more than one
occasion and that it made him so uncomfortable he told his mother after
several months that he never wanted to see Ayres again.

   Greg H.'s testimony can only be used as evidence if the jury finds
it credible.

   Ayres was arrested in April 2007 and has been free on $750,000
cash bail.

   Six witnesses have testified in the trial, and four other men
whose claims fall outside the statute of limitations have also addressed the
court, but it is up to the jurors whether their testimony can be used as
evidence.

   Ayres earned his medical degree from the University of Wisconsin
in 1956 and was president of the American Academy of Child and Adolescent
Psychiatry from 1993 to 1995. He moved to the Bay Area with his wife in 1963.

   He said Wednesday that he treated thousands of patients and conducted
tens of thousands of sessions while practicing psychiatry, and that he didn't
recognize any of the witnesses who testified against him in the trial.

   Weinberg said during opening statements that the alleged victims'
memory of events should be questioned because of the amount of time between
when the alleged crimes took place and when they came forward with their
claims -- years after the alleged molestations took place.

  McKowan, however, has said the witnesses' accounts are accurate
and credible.

   Ayres' testimony is expected to continue Thursday.