When considering hearsay statements by a co-defendant that tend to implicate another defendant, the critical aspect that determines whether the truth of the matter asserted can be admitted despite the Confrontation Clause is not the indicia of reliability from some preconceived litmus such as the testimonial form of the statement, but rather the totality of the circumstances.
http://www.opn.ca6.uscourts.gov/opinions.pdf/18a0212p-06.pdf
Since 2011. An occasional commonplacing of the U.S. Circuit Courts of Appeal.
Neither an authoritative statement of the law nor legal advice. Quick work.