A statement is not hearsay if offered against another party, and if that party is the declarant personally or in a representative capacity, or if the party had expressed belief in the statement's truth; or, if the statement is made by an agent of the party against whom it is being offered and concerns a matter within the scope of the employment and is made during the course of that employment. Also, if the declarant was a co-conspirator of the party and the statement was made during the course and in furtherance of the conspiracy, it is not hearsay.