LANSING, Mich. (AP) — The Michigan attorney general’s office said Tuesday that the state prosecution of former Gov. Rick Snyder and other officials for their roles in the Flint water scandal has ended.

A decision Tuesday by the state Supreme Court to decline to hear appeals of a lower court’s dismissal of misdemeanor charges against Snyder “effectively closes the door on the criminal prosecutions of the government officials,” prosecutors said in a release.

“At this time the court has left us with no option but to consider the Flint water prosecutions closed,” the prosecution team said.

The Michigan Supreme Court in September rejected a last-chance effort by prosecutors to revive criminal charges. The attorney general’s office used an uncommon tool — a one-judge grand jury — to hear evidence and return indictments against nine people, including Snyder. But the Supreme Court last year said the process was unconstitutional, and it struck down the charges as invalid.

Snyder was charged with willful neglect of duty. The indictment against him also was dismissed, though the Supreme Court did not address an appeal by prosecutors in September only because that case was on a different timetable.

The Associated Press left a text message Tuesday seeking comment from Snyder’s attorney.

Managers appointed by Snyder turned the Flint River into a source for Flint water in 2014, but the water wasn’t treated to reduce its corrosive impact on old pipes. As a result, lead contaminated the system for 18 months. Some experts have attributed a fatal Legionnaires’ disease outbreak in 2014-15 to the water switch.

Flint was reconnected to a regional water system in 2015 and has been compliant with lead standards for seven years, regulators said.

Snyder, a Republican, acknowledged that state government botched the water switch, especially regulators who didn’t require certain treatments. But his lawyers deny his conduct rose to the level of a crime.

“Our disappointment in the Michigan Supreme Court is exceeded only by our sorrow for the people of Flint,” the prosecution team said.

The prosecution team said Tuesday that it expects next year to release “a full and thorough report” detailing its efforts and decisions.

Separately, the state agreed to pay $600 million as part of a $626 million settlement with residents and property owners who were harmed by lead-tainted water. Most of the money is going to children.