Six psychiatric experts have now testified in the Lindsay Clancy murder trial, three for the defense and three for the Commonwealth. On the question the public thinks the case turns on, they agree. Every one of them accepts that Clancy was mentally ill on January 24, 2023. The prosecution has never argued otherwise.
So what are they fighting about? A distinction that Massachusetts law draws sharply and that almost nobody outside a courtroom draws at all.
Illness is not the question the jury answers
The standard comes from Commonwealth v. McHoul, decided by the Supreme Judicial Court in 1967. A person is not criminally responsible if, at the time of the conduct, as a result of mental disease or defect, she lacked substantial capacity either to appreciate the wrongfulness of her conduct or to conform her conduct to the requirements of law.
Notice what the test does not ask. It does not ask whether she had a diagnosis. It does not ask how much she was suffering. It asks about two specific capacities, and it asks about them at one specific moment. A woman can be severely, genuinely, documentably ill and still be criminally responsible under this standard, if the illness left those two capacities intact.
That gap between illness and incapacity is the entire trial.
What the defense experts concluded
Dr. Phillip Resnick, the forensic psychiatrist who evaluated Andrea Yates and who examined Clancy at Tewksbury State Hospital, told the jury she suffered postpartum psychosis with command hallucinations, that she felt her body had been taken over by an external force, and that she was, in his words, frankly psychotic and not criminally responsible. A second defense psychologist reached the same conclusion, testifying that she did not appreciate the wrongfulness of what she was doing.
The defense supported that with history rather than diagnosis alone: roughly ten psychiatric medications in her final months, an admission to McLean Hospital about a month before the killings, and a December 2022 conversation in which she told her mother she was having thoughts of harming her children and said, “This isn’t me. I just want to feel better and enjoy my kids again.”
What the prosecution experts conceded, and where they stopped
Here is what makes this trial unusual. The Commonwealth did not put on a single witness to say Clancy was faking or well.
Dr. Avram Mack diagnosed a major depressive episode and told jurors that “there’s no reason why psychosis in and of itself inhibits a person from knowing right from wrong.” Dr. Kirk Heilbrun diagnosed bipolar II disorder complicated by insomnia and by her medications, then testified: “She retained an awareness of the illegality of killing people, including killing her children. My clinical opinion is that she was criminally responsible on January 24.” Dr. Gregory Saathoff, the FBI forensic psychiatrist who was the trial’s final witness, focused on the reported command voice and told jurors that “committing the act is not curative of the voice. I’ve not ever seen that.”
Three experts, three diagnoses, one shared conclusion: she was ill, and she knew.
The two competing stories of that night
Strip away the credentials and the jury is choosing between two accounts of the same forty-five minutes.
In the defense account, a woman in the grip of postpartum psychosis hears a voice she experiences as external and overwhelming, loses the capacity to resist it, and does something her illness rather than her will produced.
In the prosecution account, a profoundly depressed and suicidal woman decides to end her life, cannot bear to leave her children behind, and kills them because she believes they would be better off dead than living without her. Heilbrun put that motive in explicitly sympathetic terms: she loved them. It is a story of terrible illness and terrible choice at the same time, and under McHoul the choice is what matters.
The Commonwealth also offered jurors a way to accept Clancy’s own descriptions without accepting psychosis. Heilbrun described peritraumatic dissociation, an experience during traumatic circumstances in which, as he put it, “things are unreal, it sounds psychotic but it happens when going through a traumatic set of circumstances.” If jurors take that route, they can believe she experienced something strange and still find she was responsible.
Who has to prove what
This is the piece most people get backward, and it favors the defense.
Clancy does not have to prove she was insane. Once lack of criminal responsibility is fairly raised, the Commonwealth carries the burden of proving beyond a reasonable doubt that she was criminally responsible. A juror who finds the expert testimony genuinely balanced has not reached a tie. Under the instruction that juror will receive, a reasonable doubt about capacity means the Commonwealth has not met its burden.
That allocation is why experienced Massachusetts defense lawyers rate this case as far more open than public opinion does, and why a hung jury is a real possibility alongside the verdicts.
What happens next
Dr. Saathoff finishes Wednesday morning. Closing arguments are expected Thursday, with the defense arguing first and the Commonwealth last, followed by Judge William Sullivan’s instructions and the start of deliberations.
More coverage: the FBI expert’s testimony Tuesday afternoon, the Day 20 morning session, what each side will argue in closings, the case for and against conviction, and the full trial timeline.
Questions readers keep asking
Do the prosecution experts say Lindsay Clancy was mentally healthy?
No. All three Commonwealth experts acknowledged mental illness. They diagnosed major depression, bipolar II disorder, and related conditions, and disputed only whether the illness left her unable to appreciate the wrongfulness of her conduct.
What is the difference between mentally ill and criminally responsible?
Under Commonwealth v. McHoul, a defendant is not criminally responsible only if mental disease or defect left her without substantial capacity to appreciate the wrongfulness of her conduct or to conform her conduct to the law. Illness alone is not enough; it has to have taken one of those capacities away.
Who has to prove insanity in Massachusetts?
The prosecution. Once the defense raises lack of criminal responsibility, the Commonwealth must prove beyond a reasonable doubt that the defendant was criminally responsible.
What is postpartum psychosis?
A rare and severe psychiatric emergency that can follow childbirth, involving hallucinations, delusions, and loss of contact with reality. It is distinct from postpartum depression. The defense argues Clancy was experiencing it; the Commonwealth’s experts diagnosed depression and bipolar II instead.
Can the jury find her guilty of something less than first-degree murder?
The verdict options are set when the judge instructs the jury. Second-degree murder, which carries life with parole eligibility after 15 to 25 years, is the traditional middle option in a case like this.