men believed to be masterminds of plot ` scouted ' police stations to attack .
alleged ringleader held under tough anti-terror laws without being charged .
friend of the teenagers reveals the moment they ` became radicalised '
killing of numan haider last year said to be when they became extremist .
also revealed teens were being recruited of top isis official , neil prakash .
instagram account of sevdet besim give insight into the mind of the teen .
he was one of five men arrested as part of anti-terror raids in melbourne .
police allege the teenagers planned to target an anzac day ceremony .