Reddit reviews The Unabomber and the Zodiac

In general, what links them together is:

• caucasian male, 25-40 years old at the time of the Zodiac crimes
  
• similar pathologies (social & sexual problems), going by the Zodiac's victimology (mostly attacking couples) and Kaczynski's known life history
  
• above average intelligence
  
• mechanical skills, especially bomb-making
  
• use of elaborate ciphers (two of Zodiac's ciphers haven't been cracked yet)
  
• obsessed with notoriety, media attention (both sent letters to major newspapers demanding the publication of some material)
  
• similar handwriting, style, and composition
  
  Here are a few specific pieces of evidence linking Kaczynski to the Zodiac:
  
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  Kaczynski's facial features match the San Francisco composites of the Zodiac, especially the strong chin (this is a long shot, but composites are never perfect): link
  
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  The similarity between the Zodiac symbol and a unit circle (note the marks drawn on the Zodiac symbol by the murderer himself that indicate it may not simply be a crosshair): link
  
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  The similarity between the Zodiac symbol and the graffiti used by Kaczynski as the Unabomber (based on descriptions by victims): link
  
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  The similarity of the diagrams drawn by Kaczynski and the Zodiac: link
  
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  The clues embedded in the Zodiac's three part cipher, e.g. MATHITEACH, TEDANDDAVE (bolded, vertically): link
  
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  The similarity of their handwriting, once blurred (can you tell the difference?): link
  
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  The same picture as above, unblurred (note how strongly similar the handwriting is): link
  
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  The use of a horizontal freehand line to separate different sections of text: link
  
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  The use of hanging indents to enumerate items (very mathematical): link
  
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  There are many other pieces of indirect evidence that Kaczynski is the Zodiac. All the figures above are taken from this book, by the way. The free preview is worth reading. Of course, none of this is conclusive until we have hard evidence (which may never happen), but Kaczynski is by far the best Zodiac suspect, in my opinion.