The revelation that the confidential FBI informant who first connected Sen. Nathaniel T. Oaks with what turned out to be a bribery sting is former Baltimore County schools official Robert J. Barrett presents some additional intrigue for the case against the lawmaker. Mr. Oaks’ attorneys are already arguing that Mr. Barrett’s participation taints the case against their client because he was motivated to set Mr. Oaks up to secure a lighter sentence for himself. But it’s also a bombshell in Towson.

Mr. Barrett is not some minor figure in county political and government circles; he was former County Executive C.A. Dutch Ruppersberger’s campaign manager and the political Mr. Fix-It of his administration. He was former County Executive James T. Smith Jr.’s first appointment when he took over in Towson in 2002, serving as director of Recreation and Parks, and eight years later, then-Superintendent Joe A. Hairston hired him to run government and community relations at a time when he was faring poorly on both fronts. When the deals were getting done at the Towson Diner, Mr. Barrett was usually in the booth.

From the FBI’s perspective, Mr. Barrett’s cooperation in the investigation leading to the Oaks indictment and his guilty plea on tax charges may close this chapter in this matter. But his retirement Thursday — two days before William F. Zorzi of Maryland Matters broke the story of his guilty plea — shouldn’t be the end of the matter for the county schools or government.

According to court documents in the Oaks case, Mr. Barrett accepted $22,000 in bribes from undercover FBI agents in 2013 after having accepted $37,500 in cash and checks from two, unnamed county businesspeople in 2011, 2012 and 2013. There is no indication that Mr. Barrett’s activities were related to those that led to former Superintendent Dallas Dance’s indictment this year on allegations that he failed to report tens of thousands of dollars in outside income. Indeed; the chain of events that led to Mr. Barrett’s involvement in the case began before Mr. Dance even applied to be county superintendent. But the coincidence underscores the necessity for the school board to evaluate its oversight of the district and lends support to Gov. Larry Hogan’s call for an inspector general to investigate accusations of wrongdoing in local schools. Opponents’ arguments that local systems are already subject to sufficient oversight are increasingly untenable.

The county government has reason to be concerned, too. Although Mr. Barrett played no role in County Executive Kevin Kamenetz’s administration, he had been an extremely influential figure in Towson for the previous 16 years. Were any of his actions or decisions during that time dishonest or corrupt? Moreover, two unnamed members of Baltimore County’s business community were evidently willing to hand over tens of thousands of dollars to Mr. Barrett not just because of his position in the school system but also because of his supposed continuing influence in county government, court records show.

The County Council, the county’s legislative delegation in Annapolis and State’s Attorney Scott Shellenberger need to do what they can to learn the full story of Mr. Barrett’s admitted corruption. In the days of Spiro Agnew and Dale Anderson, envelopes of cash were the way business was done in Towson. County residents deserve to be confident that things have really changed.