My boss asked me to interview a construction executive job seeker, which he felt was a perfect fit for our organization. During my interview, I could not help but to think that this person is lying about his prior accomplishments.

As an experienced interviewer, sometimes you have to follow your gut instinct. There are ways to verify any information given in an interview setting.
For instance, ask the construction executive job seeker to describe a work experience they have had that is related to a specific job related skill you are attempting to evaluate. As the construction executive job seeker responds, probe for detailed information.
Be sure to take notes as the construction executive job seeker responds. Then say, "Who can I talk to in order to verify the information you have just given me?" Be sure to contact this person as part of your reference checking process.