I disagree. I think that is a presumption, and a guess. I certainly wouldn't think this way. He MAY have had a knife, which he may have produced later. But I don't know how many times it has to be said that he did NOT have a gun in any of that video - OR a knife. It is fringing artifact. You can clearly see the black shadow around and along the edges of every light-coloured object (eg his hand).
I really don't think he had ANY weapon with which he would threaten Jill - not at that time anyway. If he did - then WHY did Jill walk in the same direction he did? There were other people about on Sydney Rd - if he was waving knife or a gun at her, surely she would have simply run the other way and screamed. She looked WAY too calm on the CCTV footage.
Nope - I think he didn't need any threatening weapon. He somehow convinced her that she was safe - either by leaving and turning the corner, or by convincing her that somebody MORE dangerous was following her. So much so that she FOLLOWED him. There's no way I could see her doing that if he was threatening her with a gun. And to threaten somebody with a knife, you have to be up in their face almost - not several paces away and leaving her standing still....
EDIT: one other point springs to mind - and the legal types on here can correct me if I'm wrong on this... but if he DID have a gun or a knife, then wouldn't the charge involve ARMED abduction or however it is worded? Or going armed in public, or some such? If the police really thought he had a weapon?
The other point is that the "gun" shadow is actually too small to be a real gun. I don't know how many of you have actually handled a real small-arm (I have - many times) but something of the size that is suggested in those still frames would be a fake cigarette lighter pistol or a toy at the most. If it were real. Which I'm sure it wasn't...