The Chicago Tylenol Murders

Imagine a time when there was no tamper proof packaging on your medications. I know it sounds like it was a bazillion years ago but nope it was just the 80s. Yes, the oh so sweet & naive 80s. Within a ridiculously short amount of time 7 people had died in the Chicago area immediately after taking extra strength Tylenol. Was Chicago cursed? Were these people just terribly unlucky? Or... was it murder?