Donahue Investigative Services & Executive Protection is a licensed private investigation firm serving New Hampshire and Massachusetts. We are led by former law enforcement officers with more than 56 combined years of experience — and we bring that same discipline, discretion, and evidentiary rigor to every case, whether for a private client, an attorney, an insurer, or a business.
We believe an investigation is only as valuable as the evidence it produces. That’s why everything we do is built to hold up — gathered legally, documented thoroughly, and formatted for court or professional use from the start.
Our Investigators
Mark J. Donahue — Founder & Principal Investigator
Mark is a former Salem, NH police officer with a 34-year law enforcement career. His assignments included service on the DEA Task Force, the Internet Crimes Against Children (ICAC) Task Force, and the New Hampshire Attorney General’s Gang Task Force — federal-level investigations demanding sophisticated surveillance, meticulous evidence handling, and inter-agency coordination. That experience is the foundation of the firm. Mark holds NH PI License #M-2025-0424 and MA License #LP1599A.
Joseph E. McCain — Senior Investigator
Joseph brings more than 30 years of law enforcement experience, including 26 years with the Somerville, MA Police Department, where he retired as a Lieutenant. His career in the heart of the greater Boston area gives the firm deep knowledge of Massachusetts communities and courts, and his background with NH DHHS adds specialized expertise in family-related investigations. Joseph is licensed in both NH and MA.
Why Clients Choose Us
- Former law enforcement — 56+ combined years, including federal task force experience
- Dual-licensed in NH and MA — no jurisdictional gaps when cases cross the border
- Court-admissible evidence — gathered within NH and MA law, with documented chain of custody
- Confidential and discreet — professionalism on every case, large or small
- Available to testify — deposition and trial testimony when your case requires it
Who We Serve
We work with private individuals, family law and divorce attorneys, insurance special investigation units, defense and plaintiff counsel, and businesses across New Hampshire and Massachusetts — from Salem, Manchester, Nashua, Concord, and Portsmouth NH to Boston, Worcester, and Lowell MA, and the communities in between.
Contact Us
Call 603-785-2800 for a free, confidential consultation. Donahue Investigative Services & Executive Protection — NH License #M-2025-0424 · MA License #LP1599A.
