There are LOADS of synth sounds in Prodigy tunes that are samples. You just have to know the original tunes they're sampled from in order to recognise them. One that springs to mind is The Heat, The Energy on the Jilted Generation album which samples Lil Louis - I Called You (Why'd u Fall) I agree, it is almost certainly a sample from Homicide, the noise was very widely used in hardcore tunes at the time.