The fact that several people said she was there one minute and gone the next really suggests there was no to-ing and fro-ing between Christine and whoever offered her a lift - it makes you think she must surely have known that person well to get into their vehicle. Similarly with the cigarette burns mentioned by the ME- it brings to mind a younger person, who could have been in her peer group. I bet somewhere in that 500-strong list of people interviewed and let go again is the killer.