A word to describe an incident or event that may or may not have taken place

Is there any word that can be used to describe an incident or event that may have taken place but people are not sure if that event actually took place because there is a lack of comprehensive evidence.

For example many people believe that the Roswell Incident is actually true, however others believe that such an incident did not take place.

Another example is an event from an Eastern religion called Mahabharat that is considered to be true by many people, however others differ suggesting that there is no conclusive evidence to suggest that this event actually took place.

purported - said to be true or real but not definitely true or real

If things are more certain, you can bump the status of a purported event up to putative:

putative - generally believed to be something

Consider alleged

Represented as existing or as being as described but not so proved; supposed: an alleged conspiracy; an alleged traitor; an alleged victim of a crime.

American Heritage Dictionary

Similarly claimed

to say that something is ​true or is a ​fact, ​although you cannot ​prove it and other ​people might not ​believe it

Cambridge Dictionaries Online

Also

• supposed
• declared
• assumed
• so-called
• apparent
• rumoured
• stated
• described
• asserted
• presumed
• affirmed
• professed
• reputed
• hypothetical
• averred