I wonder if the image is actually from a police car dash cam? Perhaps a witness statement from the day of the crime gave a description of slim man, dark wavy hair, blue jacket and distinctive Nike bag. Then LE who were working at scene of crime read witness report and said ‘hang on, we drove past him the day after the murder’. They find the pic, show the witness who says ‘yes that’s him’.
But no one locally knows who he is as he either is new to area or keeps himself to himself for whatever reason (plus recent covid lockdown). So LE are forced to make a public appeal. When the photo comes out CW realises he is a marked man especially living so close to the crime scene so tries to make his escape. He might even have caught the train from Aylesham. Dover is only 4 stops away although 13 miles not the 8 miles from home he was reportedly arrested.