Jamie Sullivan



  • Land
  • Office
  • Investment Sales
  • Client Representation
  • Consulting


Jamie Sullivan, a native of San Antonio, has been practicing commercial real estate brokerage in the San Antonio and South Central Texas market since 1984, previously with national and regional firms before forming Sullivan Commercial Realty in 1997. He began his career engaging in brokerage for international firm, Fuller/Le Page Properties, and then for regional operation of Commercial/Industrial Properties. For nine years, Sullivan was an associate with Sage Western Companies, a successful local commercial real estate investment, development and brokerage firm.

Sullivan has been a consistent leader in office and land brokerage throughout his career.

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  • Sullivan was the primary agent on behalf of a private client in the disposition of the 650,000 SF Houston/Vise Oaks office portfolio for approx. $56,000,000. Sullivan had assembled the portfolio on behalf of client Vise Oaks in a series of one off transactions.
  • Negotiated on behalf of Vise Oaks I, Ltd., Seller, in the acquisition and subsequent sale of 129 acres known as Point Northeast located at Loop 1604 E @ IH-35N for $24,000,000 to the developer of Gateway Plaza, 850,000 SF retail development.
  • Represents the Davis-McCrary Property Trust in the marketing of over 1,400 acres in Bexar County. Negotiated land sales on behalf of Seller to Northside ISD for development of school sites and 90+ acres to Pulte Homes for residential development.
  • Negotiated on behalf of the San Antonio Fire & Police Pension Fund in the acquisition of over 176,000 SF of Class A office building sales, including a new corporate headquarters office location for the fund and disposition of former headquarters building.
  • Represented CST Brands, Inc (CST) in site selection / acquisition of the 92 acre corporate campus including 500,000 SF office/warehouse/distribution center and subsequent office lease of 120,000 SF to Pearson Education (PE).
  • Negotiated on behalf of Schertz-Cibolo-Universal City ISD in acquisition of the 100+ acre future high school site. Currently represents the District in search of school sites / land.
  • Currently handles the most significant multi-use land tract in Bexar County, the 3,200 acre Village at West Pointe in far west San Antonio adjacent to Westover Hills & Alamo Ranch. Sullivan has closed on over 400+ acres in land sales to residential land developers with negotiations pending on commercial, retail and multi-family sites.

Real Estate Council of San Antonio
International Council of Shopping Centers (ICSC)
San Antonio Board of Realtors
South Texas Commercial Association of Realtors
San Antonio Chamber of Commerce

Pete Tassos



  • Office Leasing
  • Land
  • Investment Sales
  • Tenant Representation
  • Landlord Representation
  • Consulting


Pete Tassos has been involved in real estate brokerage in San Antonio since 2001, joining Sullivan Commercial Realty in 2004. Tassos is actively involved in assisting clients, whether small office users, corporate businesses / institutions or land owners, in the acquisition of office space for lease, building purchases and raw land.

Tassos is one of the leaders in San Antonio Tenant / Landlord / Owner Representation – represents various clients from public entities to small business in all aspects of real estate including office, medical, industrial, retail and land.

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Tassos’ successful working relationships with his clients is reflected by continued and repeated representation in all aspects. Sullivan Commercial/Tassos is the Exclusive Agent on assignments for Generations Federal Credit Union and the San Antonio Fire and Police Pension Fund to name a few.

  • Tassos negotiated in the lease of 23,000 RSF, a new headquarters location for GFCU at the SWBC Tower. Tassos negotiated the sale of GFCU’s previous downtown headquarters location in 2010, as well as the disposition of former GFCU retail banking sites.
  • Tassos negotiated on behalf of the San Antonio Fire and Police Pension Fund, in the purchase of Parkway Center, an approx 69,530 sf office building, located at 11603 W. Coker Loop. Subsequently, Sullivan Commercial Realty was awarded the property management and leasing contract for Parkway Center. Tassos negotiated on behalf of Landlord to absorb over 48,000 sf within six months to bring the project to 100% occupancy.
  • Negotiated on behalf of the San Antonio Fire & Police Pension Fund in the investment acquisition of over 106,000 SF of Class A office and disposition of former headquarters building.

Recent headquarters transactions include CST Brands, SA Fire & Police Pension Fund, Generations Federal Credit Union, Ricos Products and Regent Care.

  • Represented CST Brands, Inc (CST) in site selection / acquisition of the 92 acre corporate campus including 500,000 SF office/warehouse/distribution center and subsequent office lease of 120,000 SF to Pearson Education (PE)
  • Negotiated on behalf of Allergy, Asthma & Immunology Assoc in the acquisition of a land site and building for their 4th medical office
  • Dermatology & Laser Center of SA in the sale and leaseback of Louis Pasteur location
  • Pediatric Digestive Care in the purchase of Stone Oak office/retail center where Sullivan was retained to manage and lease the property
  • Tassos successfully located and closed on a Medical Center Transit Center site for the VIA Transit Authority

Tassos is also involved in the marketing of several prominent land tracts in the Bexar County and South Texas area.

  • Sullivan Commercial/Tassos represented the Schertz-Cibolo-Universal City ISD in the land search/purchase of 101+ acre future high school site and is actively searching for sites to meet the District’s upcoming school site needs.
  • Sullivan Commercial/Tassos has more recently been selected by the Comal ISD to assist in site searches to meet their District’s school site needs.

Texas Tech University – BA
Texas Real Estate Broker License

Zach Davis



  • Land
  • Investment Properties
  • Leasing / Tenant Representation


Zach Davis has been involved in the commercial real estate industry in San Antonio and south Texas since 2005.  He began his career with a boutique appraisal firm.  During his time in the valuation industry, he obtained experience providing real estate appraisals and consultations for financial institutions, developers, property owners, governmental agencies, trust departments, accountants, and attorneys. 

His appraisal experience encompassed a wide variety of property types including office, retail, industrial, multi-family, hospitality, vacant commercial land, and subdivisions.  Mr. Davis obtained the prestigious Member of the Appraisal Institute (MAI) designation in 2014.  From 2015 to 2017, he worked with a national appraisal firm, gaining valuable insight into the intricacies and underwriting methodology of institutional-grade properties.

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His entrepreneurial spirit led him to form a real estate brokerage firm in 2010.  With a focus on the sale of rural land, he has since been involved in the sale of numerous rural properties, with total transactional volume in excess of $25 million.  In addition to rural land brokerage, he gained valuable experience participating in several tenant representation assignments.

Davis joined Sullivan Commercial Realty in February 2017 and focuses on all aspects of the operation, including leasing, land brokerage, investments sales, and consulting. 

Texas A&M University – Bachelor of Business Administration, Finance
Texas A&M University – Master of Land Economics and Real Estate
Texas Licensed Real Estate Broker

Karrie Dziuk



Karrie Dziuk has been involved in the real estate industry in San Antonio since 1992, joining Sullivan Commercial Realty in 1999.

Karrie’s specialties include marketing, research, financial analysis, asset management and development supervision. A key component of her role is developing the strategy and marketing approach for agency sales and leasing assignments. As operations manager, her responsibilities span business development, finance, operations, marketing and human resources. In addition, Karrie assists in the property management’s finance division.

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Prior to joining Sullivan, she was branch manager of a regional multi-family investment and brokerage firm where she coordinated comprehensive market research of multi-family and market trends, as well as analysis of comparable sales for the San Antonio multi-family market. During that time, Karrie engaged in multi-family property management, supervising a portfolio of over 1,700 units.

Karrie brings 20+ years of real estate experience, diverse skill sets and extensive knowledge of multiple industries within commercial real estate.

John Mansfield





John Mansfield joined Sullivan Commercial Realty in March 2021. Previously, he oversaw a Construction Management Team at JLL, responsible for an annual capital spend of $140+ million and a portfolio of 10+ million SF. During this time, he obtained experience of commercial design and construction, real estate financial reporting, and supplier and facilities management. John delivered this client over $10m in documented cost savings due to his focus on strategic sourcing, fee negotiating, and value engineering.

Mr. Mansfield is responsible for the overall property management for office, industrial and retail properties.

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Prior to his passage into real estate in 2017, John spent 12 years in the aerospace industry in various management and engineering roles. Early in his career, he worked for Boeing in San Antonio where he led an Engineering Team responsible for completely renovating some of the first 787 Flight Test aircraft. Later, John led several international projects located in Europe and Asia while working for Hong Kong Aircraft Engineering Company (HAECO). His specialties include structural design engineering, program management, business intelligence and business development.

The commonality across John’s diverse background has been the opportunity for complex problem solving and his continued desire to lead and develop others.

John has obtained a M.S. in Engineering Management from the University of Texas at Austin and a B.S. in Mechanical Engineering from Texas A&M University. He is a Certified PMP holder and a member of the Alamo PMI Chapter in San Antonio, TX.

Harold Shwiff



  • Property Management
  • Construction Management
  • Consulting


Harold Shwiff joined Sullivan Commercial Realty in April 2009; previously Regional Manager with Rouse Company / Melvin Simon & Associates and served as Sr. Property Manager for Trammell Crow Company in San Antonio, Director of Facilities Management for the Baptist Healthcare System in San Antonio. Mr. Shwiff has managed major real estate portfolios in Texas since 1974.

Mr. Shwiff, as Senior Property Manager, assists in the overall property management for office, industrial and retail properties.

Shwiff was key in Sullivan’s representation of CST Brands Corp Headquarters Office selection and construction management of the $3,000,000+, 250,000 SF Regional Distribution Center. Shwiff subsequently assisted in lease negotiations of the 120,000 SF office lease to existing occupant and performed property management of facility post-closing.

Shwiff completed the construction management of the $1,000,000+ finish-out and building improvements for the San Antonio Fire and Police Pension Fund’s headquarters space within the Parkway Center, a 69,500+ sf office building located at 11603 W. Coker Loop.

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His varied and extensive background in property management, facilities management and construction management include:

  • Rouse Company and Melvin Simon & Associates – Regional Manager. 9.5 million SF retail portfolio and operating budgets in excess of $80 million.
  • Trammell Crow Company San Antonio – Sr Property Manager. 4.5 million SF office, industrial and retail portfolio. Prepared and administered operating budgets of over $30 million.
  • Bonnet Resources Corp, Dallas – Regional VP for Asset Management. $500+ million FDIC portfolio, administered $18 million annual capital improvements budgets.
  • East Texas Medical Center Regional Healthcare System, Tyler – VP of Facilities Management. $100+ million portfolio consisting of 15 hospitals, 1.3 million square feet of medical office space. Construction supervision of new medical office and hospital renovations/expansions with more than $135 million in capital improvements budgets.
  • Baptist Healthcare System, San Antonio – System Director/Facilities Management. Directed facilities operations for 5 hospitals in the system with a capital expenditure budget of $125 million.
  • Cavender & Hill Properties, San Antonio – Director of Property Management. 8.2 million SF industrial, R&D and service center portfolio in San Antonio, Laredo, El Paso and the Rio Grande Valley. Prepared and administered operating budgets of over $65 million.
  • Birnbaum Property Company, San Antonio – Director of Property Management. 1.5 million SF retail property portfolio.

International Council of Shopping Centers (ICSC)
International Facilities Management Association (IFMA)
American Society of Healthcare Engineering (ASHE)
American Society of Healthcare Environmental Services (ASHES)
Institute of Real Estate Management (IREM)
Building Owners and Managers Association (BOMA)
American Management Association (AMA)

Laura Serna



Laura Serna joined Sullivan Commercial Realty in April 2020, previously with Stream Realty Partners overseeing an office portfolio of 301,169 square feet. Laura focuses on tenant and vendor relations, financial reporting, accounts receivable and lease administration.

She has a strong commitment in maintaining and improving landlord, tenant and vendor relations while developing and implementing maintenance strategies. She also assists in oversight of tenant build-outs and construction ensuring that landlord assets are protected and tenant’s expectations are met.

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With her comprehensive hands-on approach and thorough understanding of expenditures within the current commercial market, Laura strives for the highest net operating income feasible for our projects.

Building Owners and Managers Association (BOMA)

Jasmine Leal



Jasmine Leal joined Sullivan Commercial Realty in May 2020.  Previously with Stream Realty Partners, she served as assistant property manager supporting medical, industrial and office portfolios.

Her responsibilities as Assistant Property Manager include accounts payable, tenant relations, vendor contracts and distribution of owner financials.  Jasmine is an essential part of our team as she ensures maintenance requests are handled satisfactorily for our tenants.  She also assists with the leasing and marketing for Sullivan Commercial Realty.

Frank Vongsouvanh



Frank Vongsouvanh joined Sullivan Commercial Realty’s management division in June 2013.  Frank is responsible for various building functions and general repair and maintenance items.  He assists in the oversight of all building functions including preventative maintenance, inspections and code compliance.

Andrew Vongsouvanh



Andrew Vongsouvanh joined Sullivan Commercial Realty’s management division in June 2017.  Andrew is responsible for various building functions and general repair and maintenance items and assists in preventative maintenance, inspections and code compliance.