by Brooklyn, New York – The man accused of randomly beating a long-time subway security guard to death inside a Brooklyn station has been found mentally unfit to stand trial, a judge confirmed during a court hearing on Friday. The ruling pauses the criminal case while the suspect is committed to a state psychiatric hospital for treatment.
The decision follows a court-ordered mental health evaluation stemming from the Oct. 7, 2025 killing of Nicola Tanzi, a 64-year-old security guard who had worked at the Jay Street–MetroTech station for more than 15 years.
Court Ruling on Mental Fitness
David Mazariegos, 25, was ruled unfit after failing a psychiatric examination, according to Brooklyn Supreme Court proceedings. Judge Dineen Riviezzo ordered that Mazariegos be transferred to the custody of state mental health officials, where he will remain until doctors determine whether he is capable of understanding the charges against him and assisting in his defense.
“We will see you at some point at which you are better. Good luck with your treatment,” Judge Riviezzo said during the brief hearing.
Mazariegos appeared subdued and sleepy in court, dressed in an orange jail uniform, as he was formally committed to a psychiatric facility.
Charges Paused but Not Dismissed
Prosecutors said Mazariegos will still face first-degree murder and related charges if he is later deemed mentally fit to stand trial. Under state law, criminal proceedings are suspended — not dismissed — while a defendant undergoes psychiatric treatment.
Court officials noted that Mazariegos had a growing criminal record prior to the fatal subway attack and had struggled with instability in the months leading up to the incident.
Timeline of the Fatal Subway Attack
According to prosecutors, the unprovoked assault occurred at a security gate inside the Jay Street–MetroTech subway station in downtown Brooklyn. Tanzi, an Italian immigrant and devout Catholic, was on duty when the attack unfolded.
Mazariegos allegedly approached Tanzi and punched him in the face before knocking him to the ground.
Prosecutors said the suspect then repeatedly stomped on Tanzi until his body went “totally limp.”
The beating left Tanzi with a skull fracture, a crushed nasal bone, and multiple severe facial injuries. He was rushed to a hospital but died a few hours later.
Robbery and Arrest After the Killing
Authorities say the violence did not end with the assault. After Tanzi collapsed, Mazariegos allegedly stole the victim’s debit and credit cards and fled the station.
Prosecutors said the suspect later used the stolen cards to purchase a samurai sword. When police tracked him down and arrested him in Times Square, the weapon was reportedly found in his possession.
The case drew public outrage after Mazariegos was seen smiling with a broken tooth during his initial court appearance, a moment that deeply disturbed the victim’s family and coworkers.
Chilling Confession Detailed in Court
During earlier proceedings, prosecutors said Mazariegos made disturbing admissions following his arrest.
Authorities allege he confessed to beating and robbing Tanzi and claimed he had “taken his spirit.”
The statements, combined with the randomness of the attack, prompted prosecutors to request a mental health evaluation early in the case.
Impact on Transit Workers and Public Safety
Tanzi’s death sent shockwaves through the city’s transit system, particularly among security guards and station employees who say they face increasing danger while working late hours.
Labor advocates have repeatedly called for:
- Increased police patrols in subway stations
- Stronger barriers at security posts
- Expanded mental health intervention programs for individuals in crisis
Public safety experts note that while mental illness does not equate to violence, untreated psychiatric conditions combined with repeat criminal behavior can pose serious risks in crowded public spaces.
What Happens Next
Mazariegos will remain in a state psychiatric hospital until doctors determine whether he can be restored to competency. If he is found fit in the future, the criminal case will resume, and he could again face prosecution for first-degree murder and robbery-related charges.
For Tanzi’s family, coworkers, and the broader transit community, the ruling offers little closure but ensures the case remains active.
Conclusion
The finding that David Mazariegos is mentally unfit to stand trial halts — but does not end — the prosecution in the brutal killing of Nicola Tanzi. As the suspect enters psychiatric treatment, questions about subway safety, mental health resources, and protections for frontline workers remain at the forefront.
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