Story highlights Cevallos: In offering immunity to State Department staffer who handled Hillary Clinton's email, do prosecutors have a target in mind?

The mere fact that federal investigators are talking to the staffer doesn't mean someone will be indicted, he says

Cevallos: Those involved in dealing with Clinton emails have tough choices about whether to talk to government

Danny Cevallos is a CNN legal analyst and a personal injury and criminal defense attorney practicing in Pennsylvania and the U.S. Virgin Islands. Follow him on Twitter @CevallosLaw. The opinions expressed in this commentary are solely his.

(CNN) The Department of Justice has granted "immunity" to a former State Department employee who worked on Hillary Clinton's private email server. Bryan Pagliano initially invoked his Fifth Amendment right against self-incrimination and would not testify. Of course, the Department of Justice, known to defense attorneys simply as the "government," has many ways of getting people to talk.

The big question is whether there is a grand jury convened. The smart bet is yes. After all, the fact that there are immunity agreements logically means there's a grand jury investigation in some district. The grand jury is typically the genesis of the government's subpoena power. The next, bigger question, is whether anyone will be indicted.

The mere fact that the DOJ wants to talk to Pagliano does not mean anyone will be indicted. But if the DOJ is investigating criminal activity, they tend to find criminal activity.

In general, when the government wants to talk to someone, the person falls into one of three categories: target, subject, or witness.

If Pagliano was a "target," that generally means the prosecutor or grand jury has significant evidence connecting the person to a crime. Targets routinely become defendants. A "subject" is a midrange status; this person is part of the investigation but not quite a target; a precarious position to be in. A "witness" is a person who has valuable information, but is not (currently) believed to have committed a crime. However, "witnesses" matriculate up to "targets" very quickly, often because of the very information they provide.