Updated

Coronado police have rejected a request by the mother of a 6-year-old boy who died after falling down stairs at a California mansion to reopen the investigation into her son's death.

U-T San Diego reports that representatives of Dina Shacknai released a letter from Coronado's police chief and San Diego County's chief medical examiner that reaffirmed Max Shacknai's death was an accident.

The younger Shacknai plunged over a stairwell banister at his father's mansion in July 2011 and died from brain injuries. His father's girlfriend killed herself two days after the fall.

Investigators say the boy may have tripped while running, grabbed a chandelier, hit his back on the banister and fallen. Dina Shacknai hired an expert who said her son's death was likely the result of an assault.