New York prosecutors say a mother tossed her newborn son from a fourth-floor window of their apartment building and she has been arrested on a murder charge.

The 3-week-old baby, dressed in a onesie, was found dead on the pavement of the building's courtyard Friday.

Queens District Attorney Richard Brown says Saturday the baby, Rizwan Ahmad, fell more than 40 feet. Brown says his mother, 21-year-old Rashida Chowdhury, is awaiting arraignment on a second-degree murder charge.

It was unclear whether she has a lawyer who can comment on her behalf.

Medical examiners say the infant died of blunt impact injuries and had skull fractures and lacerations to his brain, liver and spleen.