In the months leading up to her death, Theresa Duncan experienced increasing mental distress, including symptoms of depression and anxiety. She struggled to cope with various personal and professional challenges, which exacerbated her emotional state. Her mental health began to deteriorate significantly.

Reportedly, Duncan was seeking medical and psychiatric help for her condition, reflecting her desire to address her mental health struggles. However, the treatment she received may not have been sufficient to alleviate her suffering or prevent the tragic outcome.

On July 10, 2007, Theresa Duncan died by suicide in her apartment in New York City. Her death was a profound loss to the art world and to all who knew and admired her. The specific circumstances surrounding her death remain a subject of grief and speculation.