4 Officers Promoted In Mercer Co. Prosecutor's Investigative Unit

MERCER COUNTY, NJ — Four people from the Mercer County Prosecutor's office have been promoted to new posts in the investigative unit, Prosecutor Angelo J. Onofri and Chief of Detectives Jessica Plumeri said.

Brian Kiely has been promoted to deputy chief, Nancy Diaz to captain, Richard Sheppard to lieutenant and Ahmad Mansur to sergeant.

With her oath of office, Diaz became the highest-ranking Latina in Mercer County law enforcement history.

Kiely began his law enforcement career in 1999 as a civil investigator at the Division of Criminal Justice after graduating from John Jay College of Criminal Justice. In 2000, he became a criminal investigator with the state DCJ, investigating organized crime, money laundering and narcotics.

He spent a year assigned to Newark Liberty International Airport as part of a U.S. Customs Narcotics Interdiction Task Force.

In 2006, Kiely joined the Mercer County Prosecutor’s Office, where he has spent a large part of his career dedicated to narcotics investigation. He is an expert witness in the field of narcotics trafficking and his work has helped secure convictions in homicide, racketeering and narcotics trafficking cases. In 2021, he was designated as the chief humane law enforcement officer.

Deputy Chief Kiely supervises the Community Outreach and Restorative Justice units.

A graduate of the InterAmerican University of Puerto Rico with a bachelor’s degree in criminal justice, Diaz began her law enforcement career in 1998 as a juvenile officer for the Trenton Police Department. She joined the New Jersey Division of Criminal Justice Office of the Insurance Fraud Prosecutor in 2001 as a civil investigator and graduated from the New Jersey Division of Criminal Justice Police Academy in 2003.

Diaz joined the Mercer County Prosecutor’s Office in 2005 and has worked in every unit throughout her career. In 2018, she was the lead detective in the Art All Night shooting investigation where two gunmen opened fire at a 24-hour annual community arts event and music festival in Trenton, resulting in the death of one of the gunmen and injuries to 22 people.

She was promoted to sergeant that same year, becoming the first Latina sergeant in the history of the Mercer County Prosecutor’s Office. Diaz was promoted to lieutenant in 2023 and recently celebrated her 25th year in law enforcement.

Sheppard joined the Mercer County Prosecutor’s Office in 2010 after graduating from the New Jersey Division of Criminal Justice Academy. After working in the Trial Unit for two years, he was assigned to the Special Investigations Unit/Mercer County Narcotics Task Force (SIU/MCNTF) for seven years before joining the Mercer County Homicide Task Force. He was promoted to sergeant in 2021 and has supervised the Special Victims and Internet Crimes Against Children (ICAC) units as well as the SIU/MCNTF.

During his career, Sheppard has handled several high-profile homicide and narcotics investigations, including multiple homicide investigations involving the “H-Block” gang that have led to several convictions.

Born and raised in Trenton, Mansur began his law enforcement career with the Trenton Police Department in February 2006. Upon completing the Trenton Police Academy, he was assigned to the Patrol Bureau and then the Detective Bureau.

In 2012, Mansur joined the Mercer County Prosecutor’s Office and has worked in the Grand Jury, Trial, Special Victim, Insurance Fraud and Domestic Violence units. He has also been assigned to the Mercer County Shooting Response Team and the Mercer County Homicide Task Force.

Following a promotion to officer in charge in June 2022, Mansur was assigned to the Special Victims and Internet Crimes Against Children (ICAC) units, where he oversaw the day-to-day investigations and operations of the ICAC Unit.
As an advocate for the City of Trenton, Sgt. Mansur is actively engaged in the community, attending various meetings and acting as an outreach advocate for city youth in the Trenton Public School System.

The promotions follow the June 1 retirement of Deputy Chief Bryan.