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.
Prema zajedničkoj optužnici, Mrkšić je bio komandant 1. Gardijske motorizovane brigade JNA koja je snosila glavnu odgovornost za tromesečnu opsadu Vukovara koja je dovela do konačnog pada u novembru 1991. godine.