A terrible night in 1912 left 8 people brutally murdered in their beds, with an unknown murderer on the loose... What happened and why is this case still unsolved?

Show sources used: 

https://iowacoldcases.org/case-summaries/villisca-axe-murders/

http://www.villiscaiowa.com/the-crime.php

https://www.smithsonianmag.com/history/the-ax-murderer-who-got-away-117037374/