Friday, Aug. 21: A Propofol death and a family torn

It's the drug at the center of the Michael Jackson investigation -- the powerful anesthetic  Propofol. It's also at the center of another deadly case, what experts are calling the first known case of murder using the drug. Detectives were baffled when a healthy young college student in Florida was suddenly found dead in her bed. It seemed to be a death by natural causes... until the medical examiner discovered one thing that would turn the case around: a tiny pinprick in her arm. Ultimately, it would take a determined detective, the FBI, and a chase around the world to unravel the mystery. NBC's Hoda Kotb reports on a case of "Obsession."

Also... the tale of a mother and wife, who was about to start a new life -- until someone decided to end it. Police had a strong suspect from the very beginning: her husband! But there was just one problem: They also had undeniable proof that he could not have commited the crime. NBC's Dennis Murphy brings us an intriguing case that took years to solve, and ended in a courtroom showdown pitting father against son: "Murder in the Family."

Join us Friday at 9 p.m. ET, 8 p.m. CT for Dateline NBC.