Brokerage Services Inquiries

John J. Sheahan, Jr., SIOR
Principal & Managing Broker
314 994 4176



NAI DESCO’s leadership team has on average over 30 years of local-market leading experience and unmatched depth-of-expertise across all property types and commercial real estate needs. Our Leadership team includes:

Mark J. Schnuck


As President of NAI DESCO, The DESCO Group, and DESCO Southwest, Mark Schnuck leads a strong, principal-managed team of experienced and driven retail commercial/industrial real estate professionals.  The team oversees development, acquisition, brokerage, property management, legal and market research services for corporate, institutional, industrial and individual retail property owner clients. 

Prior to the formation of The DESCO Group in 1993, Mark served in a variety of positions at Schnuck Markets, Inc. spanning market research, distribution and real estate.

Carl J. Conceller


Carl represents buyers, sellers, landlords and tenants in the acquisition, disposition and leasing of commercial property.  Carl has 37 years of experience including 10 years with a national design/build firm with nationwide responsibility, 5 years of consulting and 25 years in brokerage. He has the knowledge, skill and experience to assist his clients in the most complex transactions.

In the past 11 years, Carl has completed over 300 transactions totaling 4,247,000 square feet, valued at over $325,000,000.


John J. Sheahan, Jr.

Founding Principal

John Sheahan has been active in Commercial Real Estate since 1987.  John has completed lease and sale transactions involving office, industrial, retail, land and investment properties.

In his career, John has completed over 700 transactions valued at over $369 million dollars involving 10.3 million square feet and 297 acres.  In the last five years, John has completed 135 transactions consisting of over 2.8 million square feet and 127 acres of office, industrial, retail and land deals valued at nearly $103 million dollars.

Peter O. Sheahan

Founding Principal

Peter Sheahan has been active in commercial real estate brokerage since 1989 and has held his real estate license since 1986.

Peter has completed lease and sale transactions involving office, industrial, retail, medical, land and investment properties. To date, Peter has completed over 600 transactions totaling in excess of $800,000,000 in value. 

William R. Barnes, III


Bill has been active in commercial real estate since 2005 and specializes in retail buyer and tenant representation, landlord representation, property disposition and investment sales.  Bill has been involved in over 325 transactions totaling more than $130,000,000 in volume.  Bill has extensive experience helping clients navigate the complexities of municipal approval, permitting, planning & zoning and entitlements.

Prior to joining NAI DESCO, Bill was with Coldwell Banker Commercial for four years and before that was Director of Brokerage at Vatterott Properties where he was responsible for a commercial portfolio exceeding half a million square feet.