On 19 August 1945, in a government decree issued by the newly-independent Indonesia, Supriyadi was named Minister for Public Security in the Presidential Cabinet. However, he failed to appear, and was replaced on 20 October by acting minister Muhammad Soeljoadikusuma. To this day his fate remains unknown.[1][5] If he was alive during his appointment and took the office, he would have been aged 22 and became the youngest ever minister in the nation's history.

He was officially declared a National Hero on 9 August 1975, thus legally declaring him dead as the National Hero title is only given posthumously.