If Shakespeare contributed the additions to the 1602 edition of Thomas Kyd's The Spanish tragedy, he did so at the time he was writing Hamlet. The additions were written anonymously, but contemporary references to playwrights and their works, publication records, and documented theatrical transactions have provoked the authorship controversy for centuries. Recent studies have attempted "fingerprinting” and "DNA" analysis of verbal structures to solve the case once and for all, but this study moves beyond the (impossible) task of trying to "prove" that Shakespeare wrote the additions and instead seeks to recreate a hypothetical scenario to show why and how Shakespeare may have written them. Using the loose structure of a modern recreation of a cold-case crime, this study contextualizes the additions and the authorship controversy they have inspired, situating the case in its earlier manifestations and in present-day criticism. It will be shown why Shakespeare would have been the ideal candidate to revise The Spanish tragedy: he was familiar with Kyd's work, was known for revitalizing older works, knew the players, and was a writer for hire. It will be argued that the publisher of the additions, Thomas Pavier, followed Shakespeare throughout his career and saw a marketing opportunity to capitalize on three trends: title pages that advertised newness, nostalgia for old texts, and a market for Shakespearean language. This essay will trace the hypothetical steps to see how Shakespeare's additions might have been written, dispersed, rehearsed, acted, and printed. Ultimately, the additions will be situated as a hypothetical middle step between Kyd’s Ur-Hamlet, The Spanish tragedy, and Shakespeare's Hamlet. / text