While there's no connection between HSUS and what happened in Ohio, the involvement of some of their leadership in other actions and events (such as recruiting for a FBI designated terrorist organization, publishing the home address of an innocent family and encouraging violence, "glorifying direct criminal action against animal-rights targets", etc) have been well documented on HumaneWatch.org.

I don't think they had anything to do with it but that's more from lack of evidence then from a viewpoint that some in their organization aren't capable of such an act.