NEW YORK — The Manhattan prosecutor who helped take down Donald Trump’s company is heading the criminal investigation into Jordan Neely’s killing, the Daily News has learned. Assistant District Attorney Joshua Steinglass, a 25-year Manhattan district attorney’s office veteran, is handling the probe into Neely’s death by homicide on a northbound F train on Monday, a source told The News. Manhattan DA Alvin Bragg’s office confirmed Steinglass is handling the investigation but would not say more. The office declined to confirm reports a grand jury is expected to be impaneled next week. Prosecutor...