Ex-teacher on trial for abusing boy in SA

A former private school teacher has gone on trial in Adelaide charged with sexually abusing a boy over an eight-year period, 30 years ago.

The 61-year-old man has pleaded not guilty to the persistent sexual exploitation of the boy who was aged nine or 10 when the alleged abuse began in 1979.

He was a friend of the victim's family and would often stay overnight at their home and go on their family holidays, the South Australian District Court heard on Tuesday.

"The abuse continued, on the prosecution case, until (the boy) was 16 or 17," crown prosecutor Tim Preston said in his opening.

Mr Preston said the abuse began with the man touching the boy, usually at night, and it escalated over time.

The man, who can't be named for legal reasons, was a teacher at two schools for more than 30 years and also tutored the victim's brother.

The victim gave evidence on Tuesday but the court was closed to the public and the media.

The trial continues before a jury and Judge Paul Rice.