Clancy is charged with first-degree murder in the deaths of her children Cora, 5, and her two younger brothers, Dawson and Callan, who were 3 years and 8 months old, at their home in Duxbury in January 2023. She has not disputed that she killed them. Her defense is that postpartum psychosis left her unable to control her behavior and not criminally responsible. She has said she heard a voice telling her to kill her children and herself. Prosecutors say she "acted intentionally, rationally and swiftly" and knew what she was doing was wrong. She attempted suicide afterward and was left partially paralyzed, and she has been held at Tewksbury Hospital since. If convicted, she faces life in prison.

The September jury deadlocked 11-1. The eleven favored a verdict of not guilty on grounds of lack of criminal responsibility. The holdout was Michael Péguy Desronvil. The defense says the court should have investigated him, because he reportedly refused to follow instructions on reasonable doubt, rather than declaring a mistrial, and that double jeopardy therefore bars a retrial. Prosecutors respond that questioning a dissenting juror would have meant intruding on deliberations and coercing the jury, and that double jeopardy does not stop the Commonwealth from seeking justice for the three children. Desronvil has said he was certain of Clancy's guilt but felt ignored.

Sullivan has already turned down several defense efforts aimed at the juror. On October 21 he rejected requests to examine the juror's cell phone records and his questionnaire, calling them inappropriate intrusions on jury privacy. He also denied a request from defense attorney Kevin Reddington for an evidentiary hearing on reports of Desronvil's legal troubles and alleged phone use during deliberations. The Massachusetts Supreme Judicial Court declined an emergency request to remove or question the juror.

The prosecution has also asked for a gag order to stop attorneys from making prejudicial statements to the media, citing Reddington's near-daily news conferences. The Commonwealth says the defense has been using them to attack the juror. Clancy's team opposes the order as prior restraint and notes that there is currently no jury and no trial date. The juror's brother told the New York Post that after Reddington made disparaging remarks about Desronvil, the family was harassed and had to move to a secure location. "My family cannot leave the house," he said. "They are leaving notes at my mother's house." Prosecutors are seeking to bar what they call "prejudicial, extrajudicial statements."

Reported options for the Commonwealth include retrying Clancy for first-degree murder, pursuing a lesser charge such as second-degree murder or manslaughter, or dropping the case. A plea deal has been mentioned as a remote possibility. Reddington has said he "can't do a trial before June," meaning June 2027.