Something odd went on with three of the four United States presidents elected during the 1840s.

William Henry Harrison, James K. Polk, and Zachary Taylor all died either while in office or very shortly after leaving. This video from Business Insider tells their stories and gives a short forensic analysis of these three unexpected deaths. Ideas that their deaths could be coincidence were recently brought into question after a medical study reanalyzed the death of William Henry Harrison using his physician’s journal.

Conspiracy theories aside for a moment, what could have linked all of these untimely demises? Find out below.