The state police overtime scandal has resulted in several guilty pleas and some prison sentences for troopers charged with being paid for hours they did not work. But a federal judge who's handling the case of one trooper seems to be pushing federal prosecutors to broaden their investigation.

Northeastern law professor and WGBH News legal analyst Daniel Medwed spoke with WGBH All Things Considered anchor Barbara Howard about the case. This transcript has been edited for clarity.

Barbara Howard: Judge Mark Wolf has postponed sentencing in the case of Trooper Darren DeJong, saying that he wanted to know why other possible crimes had not been charged in the scandal, including conspiracy. So are Judge Wolf's actions in the case kind of out of the ordinary?

Daniel Medwed: I think it's very unusual, but it also is a good question to ask. The U.S. attorney's office here in Boston has issued a number of conspiracy charges recently, so it’s a very good question to ask: Why are there no conspiracy charges here?

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Howard: Wolf seemed to suggest that DeJong could provide some assistance to prosecutors in making a broader federal case, citing DeJong’s cooperation with state investigators. Tell us about that.

Medwed: It does appear as though he had provided some information to state investigators, specifically the public corruption unit of our state attorney general's office, indicating that this scandal was pretty wide-ranging and far-reaching. That intimated, of course, that there was some type of agreement, perhaps, between different members of the state police. Now in order for a conspiracy charge to ensue, there typically has to be an agreement between two or more people with a purpose to commit a crime. And conspiracy is an add-on crime — you can add it on top of a more substantive charge. So there is a hint that there might be some conspiratorial behavior.

Howard: Federal prosecutors did push back against Judge Wolf, saying that while he may think conspiracy charges could be warranted, they don't see it that way. They said that the evidence that they have does not suggest a conspiracy. Was this an overreach on the part of the judge, or is he right to ask prosecutors to reconsider?

Medwed: I think he was in the right, especially given the context. Looking again at our U.S. attorney's office, they filed conspiracy charges not only against the Newton judge, Shelley Joseph, but also against a number of defendants involved in the college admissions scandal. So this is an office that is not hesitant to file conspiracy charges. Why all of a sudden are they being a bit tentative when it comes to the state police? It is unorthodox for Judge Wolf to ask this question, but he is an iconoclast and he's not afraid to ask federal prosecutors why they're doing things and whether they should be doing more.

Howard: Judge Wolf does have a reputation for being pretty tough when it comes to public corruption cases.

Medwed: I think that's fair to say. He, after all, was one of the people who broke open the Whitey Bulger/FBI relationship scandal about 20 years ago.

Howard: That's Northeastern law professor and WGBH News legal analyst Daniel Medwed, speaking with us about Judge Mark Wolf and the state police overtime scandal. Wolf has asked federal prosecutors to broaden their case.