 Additionally, it is revealed that Zack is an excellent singer.At the beginning of the show, he had started two doctorates—one in Forensic Anthropology, the completion of which is shown on-screen in the episode "Judas on a Pole", and the other in Applied Engineering, the completion of which is referred to in "The Killer in the Concrete".His specialty, just like Dr. Brennan, is in the analysis of remains, especially identifying cause of death and weapons from marks on skeletal remains.