DNA does not ID plane as much as you want it to.
"Yes. NTSB investigators rarely encounter a scenario when the identification of an accident aircraft is not apparent. But during those occasions, investigators will record serial numbers of major components, and then contact the manufacturer of those components in an attempt to determine what aircraft the component was installed upon."
The above cited method of identification was apparently required to obtain the positive identifications of American Airlines flight 11 and United Airlines flight 175, which crashed into the World Trade Center towers.