 Elizabeth Jameson summarized her research into the question of violence,

Whether or not individual members of the Western Federation of Miners committed violent acts during the strike, violence was not union policy.It was, however, the policy of the (Cripple Creek) Mine Owners' Association, the Citizens' Alliance, and the militia.p.233 
In 1906 Rastall concluded in part, before Harry Orchard confessed to the bombing,
Concerning the crimes committed during the latter part of the strike so little evidence has been adduced, that judgment must, for the present, be suspended.Especially is this true since, at the time the outrages were committed, the district was completely in the hands of those who sought in every possible way to fasten the guilt upon the unions.p.150-152
Rastall noted that both sides had men capable of violent crimes,
Many of the men employed as guards by the mine owners during the strike were roughs of the worst type, men with criminal records either before or since that time... there were in the employ of the Mine Owners' Association during the strike men capable of almost any crime, and that, as pointed out by the unions, these men might as logically be blamed for the overt acts of the strike as any men who could possibly have belonged to the unions.