Ramsey's former house in Boulder, Colorado

BOULDER, Colorado (CNN) -- The grand jury investigating the killing of child beauty queen JonBenet Ramsey has toured the family home where her strangled and beaten body was found.

District Attorney Alex Hunter and other investigators accompanied the 12 regular and four alternate grand jurors on Thursday's two-hour tour of the Ramsey family's former home.

The grand jury, impaneled last spring following an 18-month police investigation that has resulted in no charges and no arrests, is in the sixth week of its probe.

Their presumed mission, legal experts said, was to survey the crime scene to better evaluate the murder theories presented by investigators and to gauge distances between her parents' third-floor master bedroom, the second-floor childrens' bedrooms and the windowless basement room where her body was found.

The child's body was found by her father, John Ramsey, on December 26, 1996, just hours after she had been reported missing and presumed kidnapped.

Neither parent is believed to have appeared before the grand jury yet, though both expect to be called.

Hunter and Police Chief Mark Beckner have said the parents are under an "umbrella of suspicion." Both have proclaimed their innocence in the case.

The Ramseys have sold their Boulder home and moved to Atlanta, where JonBenet is buried.