had been fingerprinting

• past perfect progressive

  past perfect progressive

  Used to describe an action that was ongoing continuously in the past up until another past event interrupted it.

  of fingerprint.
  fingerprint

  noun

  an impression of the markings of the inner surface of the last joint of the thumb or other finger.

More Suggestions

• DNA fingerprinting
• genetic fingerprinting
• finger painting
• finger-pointing
• screen-printing
• three-dimensional printing