Dr. Avram Mack, a psychiatrist and prosecution expert witness in the Lindsay Clancy trial, is “no longer employed” by Nemours Children’s Health, a company spokesperson said.

Clancy, 36, is accused of killing her children, 5-year-old Cora, 3-year-old Dawson and 8-month-old Callan, in January 2023. Prosecutors allege Clancy strangled them with exercise bands in the basement of their home while her husband, Patrick Clancy, was out running errands.

Clancy’s defense attorney, Kevin Reddington, has argued that she was overmedicated and lacked criminal responsibility due to mental illness, including postpartum depression and psychosis. She was left paralyzed from a jump from a second-story window the night the children were killed.b

After the defense rested its case on Aug. 21, the prosecution called three reʙuттal witnesses, including Mack, a psychiatrist of 22 years and a forensic consultant who conducted an evaluation of Lindsay Clancy in April 2026. He said he also reviewed Clancy’s criminal file, as well as inpatient and outpatient medical records.

On the stand, Mack said that there was never any indication Clancy experienced mania or psychosis. He also testified that experiencing psychosis does not necessarily prevent a patient from distinguishing right from wrong. Mack said Clancy suffered from a “major depressive episode” in 2022 and 2023.

ᴀssistant District Attorney Shanan Buckingham asked whether Clancy retained the ability to conform her behavior to the law and appreciate the wrongfulness of her acts. Mack said that, in his opinion, “[Clancy] had retained that capacity.”

Upon cross-examination, Reddington criticized Mack for learning about Clancy’s background only through Clancy herself, interviewing her when she was medicated in a psychiatric hospital, without interviewing other people from her life. Mack acknowledged not interviewing other sources in his investigation of Clancy.

Reddington questioned the independence of Mack’s evaluation and asked whether he had any experience treating pregnant women. Mack said he did, including leading a high-risk maternity unit. Reddington also challenged Mack when he said Clancy had exhibited life-long resistance to taking medications.

Mack resigned from his psychiatry position at Nemours on Monday, Aug. 24, the healthcare system confirmed, the second day of his testimony in the Clancy trial. His reason for resigning was not made public.

“Dr. Avram Mack is no longer employed by Nemours Children’s Health,” a spokesperson for Nemours said in a statement. “His expert-witness testimony in the Clancy trial was related to his private forensic practice, which was always separate from his clinical work at Nemours.”

Who is Dr. Avram Mack?
Dr. Avram Mack is a psychiatrist of 22 years and a forensic consultant, according to his testimony. He was retained as an expert witness by the Plymouth County District Attorney’s office in the Lindsay Clancy case.

Mack said he met with Clancy at Tewksbury Hospital in April 2026. He said that he and Dr. Kirk Heilbrun, another prosecution witness, interviewed Clancy for four to five hours on the first day.

He took the stand on Friday, Aug. 21, and finished his testimony on Monday, Aug. 24.

On the witness stand, Mack said he is currently a professor of psychiatry at Thomas Jefferson University in Philadelphia and that he sees patients at Nemours Children’s Hospital in Delaware.

Mack also works for the forensic consulting firm Park Dietz and ᴀssociates, he confirmed on the stand.

According to his LinkedIn profile, Mack is also a faculty member at the Perelman School of Medicine at the University of Pennsylvania. However, his faculty listing at UPenn says he “may no longer be affiliated with the Perelman School of Medicine.”

Mack said he attended the University of Michigan and then Cornell University for medical school. He completed his residency in psychiatry at Brigham and Women’s Hospital, followed by a fellowship in child psychiatry at Columbia University, he said. He then completed a one-year fellowship in forensic psychiatry at New York University.

Park Dietz and ᴀssociates confirmed Monday, Aug. 31, that Mack remains an independent contractor with the company. A spokesperson said they would pᴀss along a message to Mack.

Thomas Jefferson University did not respond to a request for comment.

Defense attorney Kevin Reddington cross-examines prosecution witness Dr. Avram Mack at the Plymouth Superior Court murder trial of Lindsay Clancy on Monday, Aug. 24, 2026.