I just read Christopher Buckley’s novel Wet Work & there is a scene where a man who is about to be murdered begs for a priest. The murderer calls a rectory so his victim can make his rather lengthy confession. The detective who catches the murder finds the priest who tells him about the phone call (not the contents, of course) and adds that of course it was invalid.
Is that true, and why? If the penitent made a full, sincere confession (apparently so) and the priest gave absolution (he did) how would the sacrament be invalid?
I know this is fiction, but I can imagine extraordinary real-life situations where someone might know they were about to die and have a cell phone. I am NOT suggesting that the Church should start confession hotlines.