The parents of a Utah boy found abandoned east of Boise could be indicted by a grand jury next week, Ada County, Idaho, prosecutors say.

Ada County often uses a grand jury in cases involving children, and especially in cases of child abuse, to protect young witnesses or victims, Deputy Prosecutor Jay Rosenthal said Thursday.Edward Donald Tuinman, 29, and Deborah Tuinman, 28, were arraigned Wednesday on charges of felony abandonment of a child.

Their son, 7-year-old Eddy Tuinman, was found by truck drivers at the Black's Creek exit of I-84 on Jan. 4. We was wearing only a T-shirt and had been beaten and burned by cigarettes. Officials at Boise's St. Luke's Regional Medical Center said the mentally retarded boy's nose had been broken.

He was transferred to a foster family after being treated at the hospital.

The Tuinmans are being held in the Ada County Jail on $50,000 bond each. They were arrested in Nephi, Utah, as they traveled from Washington state to Arizona. Utah and Washington authorities are investigating the possibility of child abuse by the parents while they were in their states.

Tuinman asked to enter a plea at his arraignment, but 4th District Magistrate Lewis Woods refused to accept any plea at that time. Tuinman also said he was unable to read the complaint against him.

Their preliminary hearing was set for Jan. 31. However, a grand jury indictment cancels the preliminary hearing where the public defender would have been allowed to cross-examine witnesses.