NEW YORK — The troubled Brooklyn mom suspected of drowning her three small children in the ocean off Coney Island remained inside a psychiatric facility Tuesday, with a police source describing her as “incoherent” when taken into custody. Authorities were investigating whether the deaths could be tied to possible postpartum depression, a police source told the Daily News. Likely criminal charges remained pending against young mother Erin Merdy, 30, who gave birth to her youngest child just three months ago. In an exclusive interview with the Daily News hours after the children’s deaths, Merdy’…
