VIRGINIA BEACH, JULY 6 -- As trials began today for a couple charged in the beating death of their 13-year-old adopted son, prospective jurors were questioned about their religion and views on spanking.

Michael Diehl, 42, and Karen Diehl, 36, pleaded not guilty to all charges against them in the Oct. 29 death of their emotionally disturbed son, Dominick J. (Andrew) Diehl. According to an autopsy, the boy was beaten to death in the converted school bus where the couple lived with their 17 children, 13 of whom were adopted.

The trials are expected to last two to four weeks, attorneys said. Under a two-year state experiment, cameras will be allowed in both courtrooms, but photographers were barred from jury selection today.

All of the first 21 prospective jurors questioned in both cases said they had read news accounts of the highly publicized case. But all said the accounts would not prevent them from deciding the case fairly.

Several questions dealt with corporal punishment. The Diehls have told police that their fundamentalist Christian beliefs led them to discipline their children strictly.

They said Andrew, who was born in a Chicago slum and had been abused by his biological mother, was spanked with a paddle because he stole food and defecated on family belongings.

The prospective jurors were asked repeatedly about their views on spanking children. They also were asked whether they had been the victims of child abuse or whether they knew anyone involved in child abuse.

They were asked if they attend church and their feelings about the fundamentalist Open Door Chapel, where the Diehls attend services. And they were asked their views on speaking in tongues, a practice the Diehls followed.

Michael Diehl is charged with murder, abduction, felony child neglect and two counts of malicious wounding; Karen Diehl faces charges of murder, abduction, malicious wounding and felony child neglect.

Testimony in pretrial hearings showed the Diehls kept Andrew tied naked to the floor of the school bus for up to a week. Michael Diehl told police the punishment showed the boy that his adoptive parents loved him.

The Diehls wound up in a Virginia Beach campground in the spring of 1986 after leaving their Post Falls, Idaho, home and traveling around the country for two years in the school bus.

They lived on subsidies from social service agencies for their adopted children, many of whom are handicapped. The children are now in foster care.