Don DiStefano is a retired Detective-Sergeant from the City of Vallejo in California’s San Francisco Bay Area, where he built a distinguished law enforcement career specializing in crimes against persons, with a particular concentration in homicide and suspicious-death investigations. Recognized as a Subject Matter Expert by the California Commission on POST, Don served in multiple specialized units, including the Hostage Negotiations Team, the Field Training Unit, the Solano County Sex Offender Task Force, and the Solano County Officer-Involved Fatal Incident Investigation Team. His investigative leadership and casework earned him a reputation as one of the region’s most trusted and experienced major-crimes investigators.

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After retiring from California law enforcement, Don relocated to Connecticut and joined Quinnipiac University in 2008 as the Director of Investigations for the Department of Public Safety. He now holds the rank of Captain and oversees the department’s investigative and administrative operations. In this role, he collaborates closely with Student Affairs, Human Resources, and local, state, and federal law enforcement partners. He serves on the University’s Threat Assessment Team, teaches Active Assailant Awareness, and previously served as a Title IX Investigator.

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In 2011, Don founded Madison Investigative Services, LLC, where he provides professional investigative support across a broad range of sensitive and complex matters. His casework includes workplace investigations, personal and civil matters, wrongful-death and fatal-accident inquiries, missing-person cases, and DDS/IDD abuse-and-neglect investigations. MIS has become known for its high standards of thoroughness, ethical practice, and evidence-based case resolution.

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Don gained national visibility as the Investigative Consultant for the HBO documentary series Murder on Middle Beach (2020), offering investigative direction and professional insight throughout the production. In 2024, he appeared in the Netflix documentary This Is the Zodiac Speaking, drawing on his experience from the late 1990s when he served on the Zodiac Task Force and played a key role in reviewing and analyzing evidence in one of America’s most notorious serial-homicide cases.​

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In 2022, Don was elected President of the Connecticut Private Investigators Association (CPIA), where he continues to lead statewide efforts to advance professional standards, strengthen legislative advocacy, and enhance the reputation and effectiveness of Connecticut’s licensed investigators.

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A U.S. Marine Corps veteran who served in the Military Police, Don holds a Bachelor’s degree in Management from Saint Mary’s College of California and a Master’s degree in Organizational Leadership from Quinnipiac University. His law enforcement background, military service, and extensive investigative experience continue to inform his work and leadership throughout both the public safety and private investigative communities.