Statements made by a person who believes he is about to die, concerning the immediate circumstances of his death and the person responsible for inflicting the injuries that are causing the death. These statements are admissible as an exception to the hearsay rule in murder trials where the killing of the person who made the statements is the crime charged against the defendant.
Dying declarations are generally limited to use in prosecution for murder, but they can also be used by the defendant in defense of the murder charges.
Federal Rules of Evidence, Rule 804(b)(2)
“In a prosecution for homicide or in a civil case, a statement that the declarant, while believing the declarant’s death to be imminent, made about its causes or circumstances [are admissible as an exception to the hearsay rule].”
People v. Monterroso, 34 Cal. 4th 743 (2005)
“A dying declaration constitutes an exception to the hearsay rule if the statement was made on personal knowledge and under a sense of immediately impending death. This sense of impending death may be shown in any satisfactory mode, by the express language of the declarant, or be inspired from his evident danger, or the opinions of medical or other attendants stated to him, or from his conduct, or other circumstances in the case, all of which are resorted to in order to ascertain the state of the declarant’s mind.”