The overdosed girlfriend of former Hard Rock and Morgans hotel honcho Ed Scheetz lay dead in his Las Vegas pent house for at least 17 hours before he called 911, according to a medical expert em ployed by the dead woman’s family. It is “impossible” that the married Scheetz’s 24-year-old mistress, Michelle Hatchel, was alive — as Scheetz claimed to cops — when the CEO left his Sin City pad at 9 a.m. for work on the day of Hatchel’s fatal 2007 OxyContin and cocaine overdose, according to for mer Clark County Medical Exam iner Dr. Rexene Worrell. “The time of her death was hours be fore Mr. Scheetz reports he left for work. Every formula places her death well before that time — in fact, 6-8 hours earlier,” Worrell wrote in court papers filed this month as part of the Hatchel family’s $645 million wrongful-death suit against Scheetz. Hatchel died after a night of partying with Scheetz. He has claimed that Hatchel came home at 3 a.m. He called 911 at 8 that night.