Rex Heuermann is charged with the murders of seven women killed over the course of nearly two decades starting in the 1990s.

DNA is at the core of the prosecution's case. But defense attorneys claim the science, called nuclear DNA, has never been used in New York.

A form of DNA testing is the subject of debate in court for the Gilgo Beach murder case. The defense calls it magic while the prosecution say its science. It's a form of testing never used in the New York Court System before.