The Zodiac Killer: Unleashed

 Arthur Leigh Allen: Though there were many suspects in the Zodiac case, Arthur Leigh Allen was considered the "most leading" suspect because every clue pointed to him, but the police still didn't have enough evidence to put him in jail for the crimes. Much of the evidence linked to him being the Zodiac murderer, especially the evidence found in Allen's home during a police search warrant. The only evidence found against Arthur being the Zodiac was that his handwriting did not match that of the Zodiac's.

Some evidence found:

• military boots that matched the foot prints found at the Lake Berryessa murder;
• no Zodiac letters were sent to the police station when Arthur was arrested for child molestation;
•  the day after Arthur was freed from jail the police got the first Zodiac letter after years of not receiving any;
• the infamous Zodiac symbol was on Arthur's watch;
• Arthur told his friend at the time (Donald Cheney) that he was going to call himself the Zodiac;
• police found illegal items and clues in Arthur's home which included 4 pipe bombs, 2 bottles of potassium nitrate, and a .30 caliber rifle, just to name a few.
  

 Ted Kaczynski:  A possible Zodiac suspect because he was allegedly the unibomber who lived in the San Francisco Bay Area in the 1960's. He exhibited the ability to construct bombs, which was discribed in one of the Zodiac letters sent to the Chronicle. He also would communicate with the news media after committing murderous acts similar to the Zodiac case.

Bruce Davis : Believed to be a Zodiac suspect, but did not fit the profile,  He had long hair during the time of the Zodiac's murders, which contradicts a witness' account that the Zodiac had a crew-cut.  He was a member of the Charles Manson family. As a result, all male members of the Manson family were investigated and eliminated as Zodiac suspects.  Also, his handwriting didn't appear to match that of the Zodiac's.

 Jack the Step Dad : Suspected of being the Zodiac by his own stepson, Dennis Kaufman, after he watched a documentary on the Zodiac murderer. When Jack died his family was sorting out his personal items, Dennis came across a knife with blood on it in a box, he also uncovered the Zodiac's hooded mask which was hidden in an old PA system. These items were found in Jack's spare room. Jack also left behind rolls of undeveloped film which were turned over to the FBI. The one and only roll that Dennis had developed illustrated many gruesome and graphic images.

"[It] appeared to be people who were murdered," Dennis explained.Jack's handwriting was also the same as the Zodiac's. Jack  was not thought to be the Zodiac until years after the case and he had already past away.