Doctor Details Accused Brother Killer's Mental Health Issues | COURT TV

Court TV
Court TVMar 21, 2026

Why It Matters

The expert’s findings may determine if the murder charge is mitigated by an insanity defense, shaping both the verdict and broader legal precedent on mental‑health defenses.

Key Takeaways

  • Dr. Giani Pirelli is board‑certified forensic psychologist with 14‑year practice
  • He has conducted ~1,500 evaluations and testified over 130 times
  • Retained by defense to assess New Jersey insanity defense for Matthew Herkin
  • Evaluation included 15‑hour interview, 1,000 pages documents, and video reviews
  • Findings indicate Herkin displayed flat affect and psychotic symptoms

Summary

The courtroom video captures Dr. Giani Pirelli, a board‑certified forensic psychologist, testifying for the defense in a New Jersey murder case involving Matthew Herkin. Retained to evaluate a potential insanity defense, Dr. Pirelli outlines his extensive credentials—14 years in private practice, roughly 1,500 forensic examinations, and over 130 expert testimonies—establishing his authority before the court.

He describes his standard protocol: comprehensive record review, clinical forensic interviewing of the defendant, collateral interviews with family and providers, and limited psychological testing when appropriate. In this case he conducted 15 hours of interviews across five sessions with Herkin, 10 hours with his parents, reviewed more than 1,000 pages of medical and police documents, and examined roughly 11 hours of audio‑visual material.

Key observations include Herkin’s “flat affect” and emotionless demeanor during police questioning, and his brother’s detailed account of years‑long paranoia, delusions, and hallucinations, noting an especially severe psychotic episode on the day of the incident. Dr. Pirelli stresses that while severe mental illness is evident, the legal insanity standard requires a direct link between the disorder and the criminal act.

The testimony could heavily influence the jury’s determination of whether Herkin satisfies New Jersey’s insanity statute, potentially altering the charge or sentencing outcome. It also highlights the rigorous evidentiary standards forensic psychologists must meet to serve as expert witnesses, underscoring the pivotal role such expertise plays in high‑stakes criminal proceedings.

Original Description

A doctor testified in court that Matthew Hertgen, accused of murdering his brother Joseph, has a documented history of mental health issues. Specifically, Matthew was allegedly diagnosed with bipolar I disorder, according to the doctor's testimony. The trial is a one-day bench trial, with Matthew's fate to be determined by the judge.
Watch 24/7 Court TV LIVE Stream Today https://www.courttv.com/
Join the Investigation Newsletter https://www.courttv.com/email/
Join the Court TV Community to get access to perks:
FOLLOW THE CASE:
WATCH +140 FREE TRIALS IN THE COURT TV ARCHIVE https://www.courttv.com/trials/

Comments

Want to join the conversation?

Loading comments...