Our Team

Your Partners In Success

With our team of highly dedicated and experienced professionals, and with our client as our partner, there is nothing we cannot achieve together.


Larry Debb

President & Founder

As president and founder of GSP Development, Larry Debb brings over 40 years of real estate construction, development, and ownership experience.  He is extensively involved in all aspects of GSP Development’s operations, and he is widely recognized as an industry leader for his ability to provide innovative solutions to complex problems.  In 2006, Larry co-founded GlenStar Properties, which today owns and manages over 6 million square feet of high quality office space in Illinois and Texas.  He served as a director of GlenStar, until his retirement in 2017. Larry has been involved as an owner of over $1.5 billion of real estate in his career.

John Kosich

Head of Development

As a principal in GSP Development, and a 35 year industry veteran, John Kosich leads and oversees GSP Development’s development team and provides the knowledge, energy, and commitment to consistently deliver as promised.

Stephen Rankin


With over 45 years of experience, Steve Rankin provides extensive experience in urban design, master planning, site planning, and programming, as well as expertise in multiple project delivery modes including design-bid-build, design-build, and fast-tract construction.

Keith Kelly


With over 35 years in construction and project management, Keith Kelly has the knowledge and experience to manage every level of the construction process. Keith excels at creative problem solving and value engineering, and his wide-ranging skill set ensures that he always delivers the highest quality product at the lowest possible price.

Jacki Debb

Residential Market Analysis

Jacki Debb provides expert insight into the ever changing multi-family residential market.  She has a keen understanding of key trends and shifts in the landscape which allow her to identify the factors that will ultimately lead to a successful project.

Kevin Veon

Corporate Brokerage

With over 35 years of relationship-driven experience representing both landlords and tenants, Kevin Veon provides expert brokerage, consulting, and lease negotiation skills.

Geoff Dowling


Geoff Dowling has over 40 years of real estate experience in brokerage, consulting, development, corporate planning, and investment.  He provides unparalleled expertise for acquisitions.

John Siff


John Siff has been involved in the real estate industry for over 40 years, and he has arranged, serviced, sold or purchased over $3.5 billion of real estate debt and equity during this time.

Bill Debb

Financial and Deal Analysis

As a real estate professional for over 25 years, Bill Debb provides expert market research, financial and deal analysis.  His experience as a broker, project manager, and analyst, give him the insight to look at a deal from all angles, capturing both the tangible and intangible, rather than simply looking at numbers on paper.