Search and rescue efforts always go on beyond the reasonable time you can expect to actually find a survivor. Rescuers never want to give up and family don't want them to. Someone has to tell them it's over, and it's not an easy thing to do.
I know. I was a firefighter/ first responder for 10 years. After you’ve done it for a few years you pretty much know what the deal is within an hour or so. Make your best effort but at some point the safety of the crew becomes paramount. They’re well beyond that now.