A nanny in Syosset, Long Island died after jumping into a backyard pool when her 3-year-old charge was struggling in the water. Nassau police spokesman Det. Sgt. Anthony Repalone said the boy had been wearing a life vest, but "It's possible that the 3-year-old child removed his jacket and got into the pool." The boy's mother heard the screams from the house and ran out, able to pull her son from the water but yelled......