Mark Einstein, who spent nearly four decades as a partner in CohnReznick's Bethesda office, died unexpectedly Dec. 31. He was 69.

Einstein worked from 1977 to 2016 for accounting firm CohnReznick, where he served as director of tax and real estate services.

While at CohnReznick, Einstein guided developers and investors in structuring real estate transactions with a focus on affordable housing and historic rehabilitation. The firm was previously named Reznick Fedder and Silverman and then The Reznick Group before merging with J.H. Cohn in 2012 to become CohnReznick.

After leaving CohnReznick, Einstein started his own company, Absolute Tax Credit Investments. In 2015, Einstein was named chairman and CEO of the David Reznick Foundation, a nonprofit group with a mission to promote community revitalization, preserve affordable housing and provide scholarships.

He is survived by his wife, Deidre, his children, Justin, Emily and Christopher, his brother, Larry, and his sister, Stephany Steinberg. His family is requesting donations in his name be made to the David Reznick Foundation.