Not quite the same thing, but probably has some implications. I was watching 48 hours (a repeat program) about some stockbroker accused of murdering his wife. The wife had written a letter a few days before her death saying if anything happened to her the husband was the person who did it.
Generally (it was said) such a letter is not allowed as evidence as the accused has the right to question his accuser.
Following this line, if I made a deathbed confession that together ABC and I had killed someone, it would be enough to have me slated for the crime. However, in all probability it would not be allowed in evidence for ABC.
(BTW in the television program, the Judge used his discretion and allowed the letter in as evidence. The guy was found guilty- quite startling as very little in evidence was present. At least on the show).