He was lynched in Duluth, Minnesota, by the Knights of Liberty on September 18, 1918, for renouncing his American citizenship because he wanted to avoid fighting in World War I.

On September 11, 1918, Kinkkonen[4] (who also went by the name Olli Wirta) and five others renounced their rights to U.S. citizenship because they did not want to fight in World War I.

They later published a letter from a group called the Knights of Loyalty or Knights of Liberty, a nationalist secret society and vigilante organization and possibly part of the Ku Klux Klan[10]) saying that Kinkkonen had been tarred and feathered to serve as "a warning to all slackers", a term used for men who refused to join the military.

The Nonpartisan League took issue with what they saw as the government's inaction, "[claiming] no real effort was made to determine whether Kiikonen [sic] was really a suicide or whether he was strung up by the mob.

They were one of many voluntary nationalist vigilante organizations, including the American Protective League and Boy Spies of America, encouraged by local, state, and federal government.

The threats "disclosed the existence in Duluth of an organization called the Knights of Liberty, a branch of a nation-wide society whose purpose is to stamp out pro-Germanism by the quickest and most effective methods, without recourse to legal procedure;"[24] "its members are almost wholly business and professional men of high standing, men who beyond the draft age and unfitted by years or physical condition to join the military forces of the nation, are determined to do their bit by suppressing disloyalty and seeing to it that the nation shall not be assailed from within.

[25] The Knights perpetrated a number of other similar tarring-and-feathering incidents around the same time both in nearby northern Wisconsin,[26][27] and Bemidji, Minnesota,[28] as well as in California, where they hanged a man.