Our Mission

To provide quality, professional investigative or consulting services and meet the needs of Corporate entities, the Business Community, and Private Individuals in the most practical, efficient, and effective way.

Regional, National and International Consulting and Professional Investigations

Cornerstone Consulting Services, LLC, dba Cornerstone Investigators (Cornerstone) is an investigative and consulting company providing a wide array of professional investigative and consulting services to our clients.  Mark J. Zaba is the Founding Member of Cornerstone who retired as a Special Agent with the Federal Bureau of Investigation (FBI). Our team members, who are also retired Special Agents of the FBI, have over 100 years of combined experience. Cornerstone is a full-service investigative agency and is proud to celebrate 15 years of effectively representing our clients. We are dedicated to providing clients with effective representation along with a broad range of investigative services. Since our founding, we have established ourselves as being a premier investigative and consulting firm. Cornerstone has been a trusted source for litigation support and investigative services in Philadelphia, Southeastern Pennsylvania, and New Jersey. We offer investigative and consulting services to Law Firms, Government Entities, Public and Private Corporations, Private Individuals, and Corporations across the globe.

Cornerstone is a licensed and bonded private detective business in the Commonwealth of Pennsylvania. Headquartered near Philadelphia, Pennsylvania, we combine our deep local knowledge with the expertise of world-class professionals to assist our clients in helping them to meet their needs. Cornerstone regularly performs a full range of traditional investigative services in the greater Philadelphia area. We are extremely conscious of our clients’ goals, budgets, and their deadlines.

Cornerstone provides global reach for our clients’ investigative and consulting needs by providing services through our strategic partnerships. We are networked with other former Special Agents of the FBI, other former federal agents, and other vetted investigators and consultants. Through these associations, Cornerstone offers investigative and consulting in all 50 states and most countries throughout the world.

Integrity, Expertise and Professionalism

Headquartered outside Philadelphia, we take on the most complex and confidential matters. Our promise is our Integrity, Expertise, and Professionalism. Cornerstone provides honest, confidential, and ethical services to our clients while at the same time maintaining the highest standards for professionalism. Our primary goals are to preserve client assets and maximize their profits and efficiency. We approach our clients’ issues with discreet sensitivities.  Cornerstone is uniquely positioned to offer consulting and investigative services that focus on mitigating risk or reducing unnecessary investments by our clients. Our experience and professionalism are your assurance of a comprehensive and results-oriented cost-effective investigation which is focused on client objectives.  Cornerstone’s ownership has realized consistent results from the integrity of our staff, the quality of our work, and our global network of resources. As a result, we enjoy a solid reputation for outstanding investigative expertise. We have implemented quality control standards to ensure thoroughness and accuracy in our work product. Expert witness testimony is available for select services that Cornerstone provides.

Cornerstone has provided solutions to our clients by focusing on their objectives and resolving issues that have been of concern to them.  While most of our clients are attorneys, business, or professional corporations, on a selective basis, Cornerstone will accept cases directly from private individuals.  Our investigative and consulting practices are performed confidentially, timely, and legally.  We clarify the nature of any investigation request, to determine any legalities of which must be considered prior to the investigation, and to confirm the most cost-effective and tactically correct method of proceeding with any potential assignment. Cornerstone will conduct all investigations within established legal constraints and privacy legislation and will not deviate from this policy under any circumstances. Most of our clients are attorneys, both public and non-public companies, religious institutions, and other entities that must adhere to ethical standards.  Cornerstone will never guarantee the outcome of an investigation or assessment and our fees are not subject to the outcome of any case.  The facts of the investigation will compel the results.  Our professional backgrounds are consistent with providing quality consulting services and investigations that are confidential.  Through our collective experiences and past associations, as well as our established network of trusted national and international strategic partners, Cornerstone will coordinate investigations and consulting in the United States and internationally. 

Integrity, Expertise and Professionalism

Headquartered outside Philadelphia, we take on the most complex and confidential matters. Our promise is our Integrity, Expertise, and Professionalism. Cornerstone provides honest, confidential, and ethical services to our clients while at the same time maintaining the highest standards for professionalism. Our primary goals are to preserve client assets and maximize their profits and efficiency. We approach our clients’ issues with discreet sensitivities.  Cornerstone is uniquely positioned to offer consulting and investigative services that focus on mitigating risk or reducing unnecessary investments by our clients. Our experience and professionalism are your assurance of a comprehensive and results-oriented cost-effective investigation which is focused on client objectives.  Cornerstone’s ownership has realized consistent results from the integrity of our staff, the quality of our work, and our global network of resources. As a result, we enjoy a solid reputation for outstanding investigative expertise. We have implemented quality control standards to ensure thoroughness and accuracy in our work product. Expert witness testimony is available for select services that Cornerstone provides.

Cornerstone has provided solutions to our clients by focusing on their objectives and resolving issues that have been of concern to them.  While most of our clients are attorneys, business, or professional corporations, on a selective basis, Cornerstone will accept cases directly from private individuals.  Our investigative and consulting practices are performed confidentially, timely, and legally.  We clarify the nature of any investigation request, to determine any legalities of which must be considered prior to the investigation, and to confirm the most cost-effective and tactically correct method of proceeding with any potential assignment. Cornerstone will conduct all investigations within established legal constraints and privacy legislation and will not deviate from this policy under any circumstances. Most of our clients are attorneys, both public and non-public companies, religious institutions, and other entities that must adhere to ethical standards.  Cornerstone will never guarantee the outcome of an investigation or assessment and our fees are not subject to the outcome of any case.  The facts of the investigation will compel the results.  Our professional backgrounds are consistent with providing quality consulting services and investigations that are confidential.  Through our collective experiences and past associations, as well as our established network of trusted national and international strategic partners, Cornerstone will coordinate investigations and consulting in the United States and internationally. 

Meet Our Investigators

Please visit Our Investigators page to find out more about investigations from our company.

Mark J. Zaba

Managing Member and Founding Partner

Brian P. Smyth

Founding Partner

Michael J. Armes

Senior Operations Counsel

Lisa Feix

Senior Investigator

Brendan Zaba

Director of Operations

Thomas M. Ceccarelli

Consulting and Investigative Partner

Ronald Lee

Investigative Consultant

Contact Us

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