Webster, 52, denies murdering first wife Claire Morris, 32, on an Aberdeenshire road in 1994.
In his closing speech to the jury at Webster's trial in the High Court in Glasgow yesterday, prosecutor Derek Ogg QC said: "For 17 years it was the perfect murder. He got away with it for 17 years because he made it look like an accident."
He said Webster - also accused of trying to kill second wife, Felicity Drumm, by drugging her and staging a car crash in New Zealand in 1999 - was "a brilliant criminal genius whose only flaw was he can't stop himself".
The prosecutor added that all the individual pieces of evidence against Webster, from Guilford, Surrey, came together to "form a web, a mesh, a net that caught him so fast and so completely".
Mr Ogg added: "During his evidence all Mr Webster could do was say he couldn't remember or to repeat his mantra: 'I didn't do it, OK'."
The jury was told the evidence against Webster, which came from witnesses from Scotland, Peru, America, New Zealand, Australia and the Yemen, formed a blizzard of facts pointing to him as a murderer.
Mr Ogg compared the circumstantial evidence to a 1,000 piece jigsaw, saying: "There are bits missing, but we can still see what it is meant to be."
Webster denies all the charges. The trial, before judge Lord Bannatyne, continues.