It might be true that someone who knows he's about to die have no motive to lie about something, but that doesn't mean it's a good idea to get all verbose at such moments. You might just get better:
A US man who thought he was dying and confessed to having killed a neighbour in 1977 has been charged with murder after making a recovery, US media say.See, it never pays to talk about crimes, even with one foot in the grave.* * *
Convinced he was dying after a stroke, Mr Brewer reportedly admitted to police he shot dead 20-year-old Jimmy Carroll.
The 58-year-old, who had fled Tennessee after the killing, was arrested after his condition improved, reports say.