[1] During the interwar period, Mušicki served as an aide to King Alexander and Queen Maria.

He joined the fascist Yugoslav National Movement (Serbian: Југословенски народни покрет, Збор, Jugoslovenski narodni pokret, Zbor) following the king's assassination in 1934.

[3] Mušicki was stationed in Slavonski Brod at the time of the Axis invasion of Yugoslavia in April 1941 and served as the Royal Yugoslav Army commander responsible for the railroad between Belgrade and Zagreb in the rank of colonel.

Yugoslavia was quickly conquered by the Axis powers and Mušicki remained in Slavonski Brod for several months after the conquest.

[5] He and Milan Aćimović contacted Draža Mihailović on 5 December, possibly in an effort to warn him in advance of the assault the Germans had planned, codenamed Operation Mihailovic.

[12] He was found guilty of collaborating with the Germans, sentenced to death,[11] and was executed by firing squad in Belgrade on 17 July 1946.