Rawlings' office will have to decide when charges are filed whether to keep the case in juvenile court or attempt to try the teen as an adult.
The teen's attorney, Todd Utzinger, could not be reached Friday.
Davis County Sheriff Todd Richardson said last month that the bodies of the two boys were found in their West Point home on May 22 around 7:35 p.m. He said they appeared to have suffered "penetrating knife wounds."
Deputies rushed to the home at 120 S. 1660 West after the boys' mother called 911 to report finding her 4-year-old son dead on the floor of the home, and her 15-year-old and 10-year-old sons missing.
The 15-year-old boy had been put in charge of the two boys when their mother took her other children to a dance recital at about 4:45 p.m., investigators said.
Deputies found the 10-year-old's body in another part of the house, then issued a missing person alert for the 15-year-old, who was found late that night in nearby Layton.
The Salt Lake Tribune initially reported the name of 15-year-old in an effort to help police locate him. However, following the teen's arrest, and consistent with the newspaper's policy of not naming juvenile criminal suspects, his name is now being withheld.
The teen was found walking on the street by Layton police about 11:30 p.m., some eight miles from the crime scene. Authorities said the teen did not have a weapon when he was found, but traces of blood were found on him. He was taken to the hospital to be checked out before questioning and was then booked into at the Farmington Bay Youth Detention Center on suspicion of two counts of homicide, Richardson said.