The defence just simply stated " nobody saw Jeremy Bamber"
The 2nd investigation they got an officer to explore all routes via car, walking and cycling. Suspect they believed he could have travelled by all.
Suspect settling on the sea wall for effect, 500 people were interviewed and nobody clocked him. However they didn't replicate it at night ( for obvious reasons stated)
Whether the defence should have gone down the transport route more aggressively is a matter of opinion.