Angelo's Stand ability was brought forth by the mysterious bow and arrow, and apparently they're also connected to DIO. After defeating Angelo, Jotaro thought that the danger had left the city, and tries to find the whereabouts of the bow and arrow. A few days later, Koichi is walking home with Josuke, and they pass a house that should be empty...
it's this bow and arrow that 
unleashed DIO's Stand powers.
هذا القوسُ والسّهم هما اللّذان أطلقا عنان
قِوى الستاند الخاصّ بديو
haben dieser Pfeil und Bogen
Dios Stand entfesselt.
este arco y flecha hicieron
que brotara el Stand de Dio.
este arco y flecha hicieron
que brotara el Stand de Dio.
sono quell'arco e quella freccia
a conferire i poteri degli Stand.
foi este arco e flecha que 
despertou o Stand do Dio.