Date/Year: Prior to "Tape 1, Side A" (September 9, 2017)
Explanation: Died from Car Crash — Jeff left Jessica Davis' party and got into a car accident. People thought it was because he was drunk as alcohol was found in his car, however, Hannah Baker informed everyone on the tapes in "Tape 5, Side B" that Sheri Holland had knocked down a stop sign on the road before the incident, and believed that she may have inadvertently caused the car accident between Jeff and Mr. Cantrell—because neither would have stopped without the sign—that led to Jeff's death.
Explanation: Hemorrhage from self-inflicted arms laceration (Suicide) — After going through a series of events that broke Hannah down slowly to thinking she was worth nothing—recorded on the tapes, Hannah ran a bath intending to kill herself in it. She got in it, clothed, and slit both her arms with razor blades. This caused a hemorrhage, which led her to bleed out and she eventually died.
Explanation: Natural Causes — Harrison was previously growing ill and became sick, so Nora Walker hired Amara Josephine Achola as a nurse for him, but he eventually died of natural causes.
Explanation: Killed by a fellow prisoner — Montgomery was arrested and sent to prison for raping Tyler Down. It was later revealed by Deputy Standall that while in prison, Montgomery was found dead in his cell. After Clay was part of a cover-up that pinned Bryce's murder on Montgomery to protect Alex, he began to hallucinate Montgomery out of guilt, the hallucination told him that another prisoner stabbed him three times after the prisoner was told that Montgomery was in for being a child molester. Due to Clay hallucinating Monty telling him this, it may not be exactly what happened, but it also may be the writers way of telling viewers how Monty died.
Explanation: Possible drug overdose — Amber passed away from a presumable drug overdose after returning to Evergreen. Justin Foley was informed of his mothers death in "College Interview" while in school.
Explanation: HIV-1 progressing to AIDS, resulting in terminal pneumonia and fungal meningitis — Justin collapsed at the homecoming dance in school, he was rushed to hospital. Justin was diagnosed with HIV-1 that had progressed to AIDS that resulted from his drug use and prostitution while he was homeless. It eventually developed into a terminal case of pneumonia and fungal meningitis. Everyone, including Justin, remained unaware of his condition until it turned fatal and hospitalized him.
