Marlene Warren answered the door to her home and was fatally shot by a mysterious clown, who then calmly walked away to their getaway car. Although there were eyewitnesses, circumstantial evidence, and a prime suspect, it would take over three decades for her killer to face any kind of justice.
Sources:
1) https://www.cbsnews.com/pictures/killer-clown-marlene-warren-sheila-keen-warren-florida-murder/
2) https://www.cbsnews.com/news/sheila-keen-warren-marlene-warren-murder-florida-killer-clown-case/
3) https://abcnews.go.com/US/killer-clown-victims-son-reflects-33-year-fight/story?id=98941520
