The Zodiac Killer is known as the most famous unsolved murder in US history, having remained a mystery for more than 50 years.
Zodiac murdered at least five people in the San Francisco area between 1968 and 1969 but has never been caught.
The case has proved fascinating to amateur sleuths for decades and was even made into a Hollywood film in 2007 starring Jake Gyllenhaal and Mark Ruffalo.
The internet recently broke out in frenzy when a team of journalists, intelligence officers and former law enforcement professionals called the Case Breakers claimed to have cracked the infamous killings once and for all.
The group claimed Gary Francis Poste, a former Air Force pilot from the Sierra foothills who died in 2018, was the notorious killer.
However, since then FBI has stated the case remains open with it now looking likely the theory is little more than the latest in a long line of tips and hypotheses that have lacked evidence or been debunked.
Below we look at five of the most famous theories.
Arthur Leigh Allen
Arthur Leigh Allen was regarded as the prime suspect in Robert Graysmith's books, which provided the basis for the film Zodiac.
He owned the same calibre gun as the serial killer, wore a Zodiac watch and made a series of eyebrow raising comments to acquaintances about wanting to kill people.
He was dishonourably discharged from the navy and was fired from his job at a school due to allegations of sexual misconduct.
However, his didn't match the fingerprints believed to belong to the killer.
"Allen seems like a good suspect as long as you only get information from people who think he’s guilty," said Michael Butterfield, a writer who has spent 20 years looking into the Zodiac killer.
Allen died of arteriosclerotic heart failure in 1992 at the age of 58.
Richard Marshall
Richard Marshall was accused of being the killer by police informants claiming he had hinted at being responsible himself.
He lived close the scenes of a number of the killings in the late 1960s.
However he was not thought to be a prime suspect by a policeman who had been on the case for decades.
Detective Ken Narlow said: "Marshall makes good reading but is not a very good suspect in my estimation".
Marshall died in 2008.
Jack Tarrance
Tarrance was accused by his own step son Dennis Kaufman, who believed he was a perfect match for the composite image of the Zodiac.
Kaufman provided the FBI with a number of items including a hood similar to that worn at the Lake Berryessa stabbings as well as footage on a roll of film depicting possible victims.
In 2007 a document examiner claimed his handwriting matched the Zodiac's.
However, the examiner's credibility was later called into question and the hood is believed to be far cruder than the one worn by the Zodiac. Analysis by the FBI on the items was inconclusive and Tarrance died in 2006.
Ross Sullivan
Library assistant Sullivan became a person of interest due to a possible link between Zodiac and the also unsolved murder of 18 year-old Cheri Jo Bates.
She was stabbed to death on the grounds of Riverside City College.
Sullivan's co workers said he went missing for several days after the killing.
Sketches of the Zodiac have drawn similarities with Sullivan, who wore boot soles similar to footprints found at the scene at Lake Berryessa.
He suffered from bipolar disorder and schizophrenia and died in 1977.
Lawrence Kane
A former Navy reserve, Kane worked in the same hotel as Donna Lass, a potential Zodiac victim.
He reportedly suffered brain damage after a car accident in 1962 which could have limited his potential to control urges.
He was arrested for peeping twice in the 1960s and was identified as a close match by a number of people who had brushes with the Zodiac killer. Kane died in 2010.
