Casey O’Brien is a partner in the attest department, where he leads assurance engagements across a broad range of industries, including manufacturing, real estate, retail gasoline distribution, and renewable energy. With nearly two decades of public accounting experience, he specializes in audits, reviews, and compilations of financial statements for both publicly traded and privately held companies, as well as transaction advisory and due diligence services.

He brings deep technical expertise in complex accounting matters such as business combinations, consolidations, and equity-based arrangements, including intricate partnership equity transactions. Casey is also highly regarded for his consulting work related to quality of earnings assessments and broader deal support services.

Known for his commitment to efficiency, quality, and client service, he plays a key role in developing staff and enhancing service delivery across the firm’s attest practice. Since joining MahoneySabol in 2008, he has been instrumental in leading many of the firm’s most complex engagements and fostering long-term client relationships.

Casey holds a Bachelor of Science in Accounting from the University of Connecticut.