Geneticists are joining the investigation into the Sandy Hook Elementary School massacre.

Two weeks ago, Adam Lanza, 20, went on a shooting rampage at Sandy Hook Elementary School. He also killed his mother.

The state medical examiner was asked to do a complete analysis of shooter Lanza's DNA, but they aren't looking for anything specific.

CNN's Doctor Sanjay Gupta says it is unlikely they'll find a genetic clue as to what motivated Lanza to kill 27 people on December 14th.

He adds, even if they do, there's no proof people with those genes will also copy that behavior.

Geneticists say there are genetic components to mental illness, but there are many genes involved; not just a single gene or mutation.

Lab results of Lanza's D-N-A are not expected for several weeks.