As the MAL Contends blog correctly points out, John Doe investigations in Wisconsin do not use the term "target."
Federal grand juries in Wisconsin (and other states) do designate and notify targets as "putative defendants," state grand juries in other states designate targets.
In Wisconsin John Doe probes do not designate targets.
The John Doe statute authorizes a law enforcement investigation conducted with the compulsory authority of a quasi-judicial hearing to look into if and by whom crimes have been committed, precisely to determine whether someone should become a target of a criminal complaint on the basis of the facts and testimony gathered in the probe.
In fact, the Wisconsin Supreme Court has specifically recognized that the John Doe statute does not even "require that a witness be advised as to the nature of the proceeding," and does not require that the gathering of evidence and testimony reaches a point when someone must to be advised he or she becomes an effective target of the John Doe investigation, likely to be served a criminal complaint. (Ryan v. Wisconsin, (79 Wis.2d 83 (1977)).