To me, saying someone was murdered makes it sound like a deliberate act.
Revising that to instead say he was killed, sounds almost like it happened due to a struggle or the circumstances at the scene, but not necessarily an intentional act.
I guess there is a difference, as slight as it may be.
I also suspect that struggle may have been the source of the DNA, sounds as though there may have been a wrestling match going on before the gun went off.
Murder IS homicide, but not all homicides are murders. Struggle, maybe. He said that anyone who they can think of who may have had physical contact with him or his equipment has been or will be swabbed to eliminate. I don't know what thing they found on Friday at the scene (so it wouldn't be the gun) was an item with DNA on it , but he DID say something about ballistics testing in the same paragraph so I wonder if the thing was a bullet or a casing? JMO