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Berkley, Iselin & Lotz, S.C. is a certified public accounting (CPA) firm located in Racine, Wisconsin. Our staff consists of two CPAs: Darlene Lotz and Mark Leeder, staff accountants, administrative personnel, and several part time tax preparers.



Darlene M. Lotz, CPA

Darlene was born and raised in Racine, Wisconsin. She is a graduate of J.I. Case High School. She attended the University of Wisconsin - Parkside, graduating with a major in accounting. Darlene is a member of both the Wisconsin and American Institute of Certified Public Accountants. She provides accounting services to corporate and individual clients. Darlene joined the firm in 1993.

Mark Leeder, CPA

Mark was born and raised in Greenfield, Wisconsin and is a graduate Whitnall High School. Thereafter he attended St. Mary’s University, graduating with a degree in business management-entrepreneurship. He spent nine years working for a Fortune 100 company before attending the University of Wisconsin – Parkside. There he majored in accounting and business finance, graduating in 2015. He has volunteered and worked in accounting since 2013 and joined Berkley, Iselin, & Lotz, SC in February 2020. Mark is a member of the Wisconsin and American Institute of Certified Public Accountants. He provides accounting services to business, individual, and not for profit clients. When not assisting clients, he volunteers for various local charitable organizations and enjoys spending time outdoors with his growing family. His favorite leisurely activity is playing and watching tennis.