In an interview two months after Alex Murdaugh’s wife and son were killed, investigators zeroed in on inconsistencies in what Murdaugh told authorities about their deaths, according to the videotaped discussion played Wednesday at the disgraced South Carolina attorney’s double murder trial.The interview between the state’s chief investigator and Murdaugh backed up much of what the jury had heard about the case already in three weeks of testimony — Murdaugh said he wasn’t at the dog kennels near where his wife and son were …