Henry Classification System – Primary, Secondary, Sub-Secondary, Major, Key, Final

Overview of the Henry Classification System

• Six-part alphanumeric code written in the upper-right corner of a ten-print card.
  • Parts (in filing order, left ➜ right): Key – Major – Primary – Secondary – Sub-Secondary – Final.
  • Purpose: narrows database searches by grouping cards with similar anatomical/physiological features before minutiae comparison.

Finger Numbering & Reference “Cheat Sheet”

• Numbers (always written above each rolled print):
  • Right hand: 1 = Thumb, 2 = Index, 3 = Middle, 4 = Ring, 5 = Little.
  • Left hand: 6 = Thumb, 7 = Index, 8 = Middle, 9 = Ring, 10 = Little.
• Primary-value boxes (used only for whorls):
  • 1 & 2 → $16$ each
  • 3 & 4 → $8$ each
  • 5 & 6 → $4$ each
  • 7 & 8 → $2$ each
  • 9 & 10 → $1$ each
• Sub-Secondary loop tables (mid-box figures on the cheat sheet):
  • Finger 2: $I = 1!–!9$ | $O = 10+$
  • Finger 3: $I = 1!–!10$ | $O = 11+$
  • Finger 4: $I = 1!–!13$ | $O = 14+$
  • Finger 7: $I = 1!–!13$ | $O = 14+$
  • Finger 8: $I = 1!–!10$ | $O = 11+$
  • Finger 9: $I = 1!–!9$ | $O = 10+$
    (Values memorised or read directly from the printed chart during classification.)

Primary (3rd column)

• Describes ONLY whorls.
• Written as $\dfrac{\text{even-whorl total}+1}{\text{odd-whorl total}+1}$.
  • Even fingers: 2-4-6-8-10 ➜ numerator.
  • Odd fingers: 1-3-5-7-9 ➜ denominator.
• Always add $1$ to each sum so every set receives at least $\tfrac11$.
• Range: $\tfrac11$ (no whorls) ➜ $\tfrac{32}{32}$ (all ten prints are whorls).

Secondary (4th column)

• One capital letter over one capital letter.
  • Upper (numerator) = pattern of Right Index (Finger 2).
  • Lower (denominator) = pattern of Left Index (Finger 7).
• Symbols:
  • W = any whorl type.
  • U = ulnar loop.
  • R = radial loop (capitalised because it appears in an index finger).
  • A = plain arch.
  • T = tented arch.

Sub-Secondary (5th column)

• Three letters over three letters → fingers 2-3-4 / 7-8-9.
• Rules
  1. If the print is a whorl → simply copy its tracing (I = Inner, M = Median, O = Outer).
  2. If the print is a loop → choose I or O using the ridge-count ranges in the cheat sheet.
  3. If a small letter (plain/tented arch or radial loop outside the index fingers) appears anywhere to the right of either index, the entire Sub-Secondary is cancelled.
  • Instead: use dashes to mark positions, then insert each small letter in correct order to show its location.

Major (2nd column)

• One letter over one letter, placed immediately left of the Primary.
• Fingers considered: 1 (Right Thumb) / 6 (Left Thumb).
• Symbols when thumbs are loops (use ridge-count scale printed in box 1 & 6):
  • S = Small loop (1–11)
  • M = Medium loop (12–16)
  • L = Large loop (17 +)
• Symbols when thumbs are whorls → tracing letters I – M – O.
• If either thumb is a small-letter pattern (plain arch, tented arch, or radial loop) the Major is omitted entirely.

Key (1st column, Numerator only)

• Single ridge-count number placed far left, above the Major.
• Procedure
  1. Scan fingers in numerical order until the first loop is found.
  2. If that loop is a pinky (5 or 10) → skip it and continue.
  3. Record its ridge count as the Key.
• If no admissible loop exists → no Key is written (cell left blank).

Final (right-most column)

• Ridge-count number written on the extreme right; position depends on which pinky supplies the loop.
  • If Right Little (Finger 5) is a loop → write count in the numerator.
  • Else, if Left Little (Finger 10) is a loop → write count in the denominator.
  • If neither pinky is a loop → Final is omitted.

Worked Examples (High-level)

• No Whorls Present
  • Even sum = 0, Odd = 0 → $\tfrac11$ Primary.
  • Secondary, Sub-Secondary, Major all filled with loop/arch letters.
  • Key derives from first loop; Final from right pinky if applicable.
• All Whorls Present
  • Even sum = 31 ⇒ $32$; Odd = 31 ⇒ $32$ → Primary $\tfrac{32}{32}$.
  • Secondary = $\tfrac{W}{W}$.
  • Sub-Secondary = "OMI / MOI" (tracings for 2-3-4 / 7-8-9).
  • Major = $\tfrac{O}{O}$ (outer tracings of both thumbs).
  • Key & Final absent (no loops anywhere).
• Mixed Example (16 / 28 Primary)
  • Even whorl values = 8 + 4 + 2 + 1 = 15 ➜ $16$.
  • Odd whorl values = 16 + 8 + 2 + 1 = 27 ➜ $28$.
  • Secondary $\tfrac{U}{R}$ (ulnar loop right index, radial loop left index).
  • Sub-Secondary shows mix of I/O from ridge counts and tracings; cancelled if a plain arch appears in mid-digits.

Ethical & Practical Implications

• Rapidly excludes innocent subjects (e.g., suspect with Primary $\tfrac11$ cannot have left a whorl latent).
• Enables manual filing and retrieval in non-AFIS environments; historical cornerstone of forensic identification.
• Accuracy critical: a single mis-classed loop vs. whorl misfiles the entire card set, delaying identifications.

Quick Reference Formulae

• $\text{Primary Even} = \sum_{\text{even}} \text{whorl values}$
• $\text{Primary Odd} = \sum_{\text{odd}} \text{whorl values}$
• $\text{Primary} = \dfrac{1 + \text{Primary Even}}{1 + \text{Primary Odd}}$
• $\text{Key} = \text{ridge count of first non-pinky loop}$
• \text{Final} = \begin{cases}
  \text{Right little ridge count} & \text{if right little is a loop}\
  \text{Left little ridge count (denominator)} & \text{else if left little is a loop}\
  \text{— (none)} & \text{otherwise}
  \end{cases}

Filing Order Recap

1. Sort by Primary (numerator first, then denominator).
2. Within each Primary block, sort by Secondary.
3. Next, by Sub-Secondary (unless cancelled by small letters).
4. Then Major, Key, and Final.
5. Finally, perform minutiae-level comparison on the reduced subset.