Dr. Henry Howard Holmes was on vacation in England at the time of these murders:
Murder Castle, Chicago, Ill.: H.H. Holmes’ Serial Killings Hotel:
http://www.crimelibrary.com/notorious_murders/classics/haunted_places/4.html
Brutal slashing attacks were not Holmes MO.
I saw a documentary on Holmes (on Netflix?). What a freak. The way he configured his holding cells and torture rooms was out of a Hollywood B-movie set.