In any criminal case one may be confronted with a conspiracy or conspiracy-theory. Why is this the case? For this we first have to deal with the according definitions:
A →criminal Conspiracy is:
“In criminal law, a conspiracy is an agreement between two or more persons to commit a crime at some time in the future. Criminal law in some countries or for some conspiracies may require that at least one overt act must also have been undertaken in furtherance of that agreement, to constitute an offense. There is no limit on the number participating in the conspiracy and, in most countries, no requirement that any steps have been taken to put the plan into effect (compare attempts which require proximity to the full offence). For the purposes of concurrence, the actus reus is a continuing one and parties may join the plot later and incur joint liability and conspiracy can be charged where the co-conspirators have been acquitted or cannot be traced. Finally, repentance by one or more parties does not affect liability but may reduce their sentence.”
A →civil Conspiracy is:
“A civil conspiracy or collusion is an agreement between two or more parties to deprive a third party of legal rights or deceive a third party to obtain an illegal objective. A conspiracy may also refer to a group of people who make an agreement to form a partnership in which each member becomes the agent or partner of every other member and engage in planning or agreeing to commit some act. It is not necessary that the conspirators be involved in all stages of planning or be aware of all details. Any voluntary agreement and some overt act by one conspirator in furthance of the plan are the main elements necessary to prove a conspiracy. A conspiracy may exist whether legal means are used to accomplish illegal results, or illegal means used to accomplish something legal. “Even when no crime is involved, a civil action for conspiracy may be brought by the persons who were damaged.” In the law of tort, the legal elements necessary to establish a civil conspiracy are substantially the same as for establishing a criminal conspiracy, i.e. there is an agreement between two or more natural persons to break the law at some time in the future or to achieve a lawful aim by unlawful means. The criminal law often requires one of the conspirators to take an overt step to accomplish the illegal act to demonstrate the reality of their intention to break the law, whereas in a civil conspiracy, an overt act towards accomplishing the wrongful goal may not be required. Etymologically, the term comes from Latin con- “with, together”, and spirare “to breathe”.”
Conspiracies may be an illegal offence related to the →Criminal Law Act 1977 :
“The Criminal Law Act 1977 (c.45) is an Act of the Parliament of the United Kingdom. Most of it only applies to England and Wales. It creates the offence of conspiracy in English law. It also created offences concerned with criminal trespass in premises, made changes to sentencing, and created an offence of falsely reporting the existence of a bomb.”
You may see further also at the relating terms →“Common Purpose” and for Scotland at →“Art and Part” .
So from definition we have always to deal with a conspiracy if e.g. more than one (secret or known) offender is under our witnesses. There is no upper limit but indeed.
A → “Conspiracy Theory” then is of course any theory or hypothesis of an alleged (secret) conspiracy.
“A conspiracy theory is an explanatory proposition that accuses two or more persons, a group, or an organization of having caused or covered up, through secret planning and deliberate action, an illegal or harmful event or situation.….Although the term “conspiracy theory” has acquired a derogatory meaning over time and is often used to dismiss or ridicule beliefs in conspiracies, it has also continued to be used by some to refer to actual, proven conspiracies, such as U.S. President Richard Nixon and his aides conspiring to cover up Watergate. Conspiracy theories are sometimes proven correct, such as the theory that United States President Richard Nixon and his aides conspired to cover up Watergate, as well as the theory that some of President Ronald Reagan's aides conspired to cover up the Iran-Contra affair. Katherine K. Young writes that “every real conspiracy has had at least four characteristic features: groups, not isolated individuals; illegal or sinister aims, not ones that would benefit society as a whole; orchestrated acts, not a series of spontaneous and haphazard ones; and secret planning, not public discussion. Some historians have put forward the idea that more recently the United States has become the home of conspiracy theories because so many high-level prominent conspiracies have been undertaken and uncovered since the 1960s”. The existence of such real conspiracies helps feed the belief in conspiracy theories.”
As conspiracies are always some secret agreements between some people such agreements are not easily been investigated. Thus on the other side also every seemingly not easily explainable fact in the world may be explained by a more or less →ridiculous Conspiracy Theory. The nicely list at Wikipedia shows some of the widespread mostly unsustainable such theories.
The ridiculousness of most such common conspiracy theories but unfortunately give those who actually indeed do conspire the possibility to ridicule any assignable accusation presented as a ludicrous (Conspiracy-)Theory. So there is of course a large difference in the credibility of Conspiracy Theories, depending on how much they are provable. An incomplete list of yet proven political Conspiracies may also be found at →Wikipedia. A nice article is also to be found at →My Little Underground: When Conspiracy Theory Becomes Real Thanks To Leon Brittan
Regardles if one prefers the Accidential Killing Theory or the Abduction of Madeleine Hypothesis we will have to deal with Conspiracies.
In the case version 1 the Accidential Killing Theory we have to deal at least with:
In the case version 2 Abduction of Madeleine Hypothesis we have to deal at least with:
In practically all cases a criminal investigator will be confronted with at least some witnesses who lie. And just from definition, in virtually more than 90% of cases he will also be confronted at least with a small conspiracy. So after collecting all evidence and combining them in a logical way, one has to find out
So is the first question: Why do People lie?
Second question is, how do we find out?