What follows is an imaginary scenario and in no way represents what actually happened.
Gerry to Jane: Hey Jane, I know we don't know each other all that well but I really need you to do me a big favour. I need you to say you saw me last night to provide me with an alibi cos I was seen carrying the body.
Jane: OK, what time were you spotted?
Gerry: About 9.50 - just about 10 minutes before Kate raised the alarm
Jane: OK - what would you like me to say?
Gerry: That you saw me talking to that Gez bloke on the street near the apartment.
Jane: OK - what time was that then?
Gerry: Erm...well I'm not sure. Couldn've been anything up to an hour before I was spotted carrying the body.
Jane: How does that actually provide you with an alibi though?
Gerry: Erm...dunno. Just say it though would you?
Jane: Sure, no problem.
Gerry: make sure you say about the flip-flops. Oh, and by the way, when they ask me I'll say I never saw you, OK?
Jane: Oh. Why not?
Gerry: Well I didn't did I?
Jane: Erm....right-o then.