|Detroit Free Press, October 17, 1931 (enlarge)|
Two Communist inmates on a 3 day pass hatched a plot, began to assemble a bomb across the street from Henry Ford's home and in the exact spot where an eccentric man had left his shoes to go for a nice November walk in the fields nearby. When Joseph Toms returned from his walk he discovered the bomb and notified police.
The men, Frank Baker and Roy Goodwin, eventually confessed and were shipped to Ionia for 4-5 years. Although they never confessed to the dynamiting of the tunnel on October 6th it seems likely that they were behind the attack.