Prema zajedničkoj optužnici, Mrkšić je bio komandant 1. Gardijske motorizirane brigade JNA, koja je snosila osnovnu odgovornost za tromjesečnu opsadu Vukovara, koja je dovela do njegovog konačnog pada u novembru 1991.
According to the joint indictment, Mrksic was the commander of the JNA's 1st Guards Motorised Brigade, which bore prime responsibility for the three-month siege of Vukovar that led to its eventual fall in November 1991.