[ConservativeWarrior]

Grisly as it sounds, good biometric authentication devices contain checks to confirm that they body part is still attached to a living individual.

Retina scanners flash a light to ensure the pupils dilate.

Finger print scanners check that a pulse is present.

[Daffynition]

Police use a cadaver digit, inside a tennis ball; and train their cadaver dogs to alert to the smell of decayed or rotting flesh.; Demonstrated, the officer hides the ball, and the dog searches it out.