More literal:
* இருந்திருக்கலாம் (irundhIrukkaLam) - This literally translates to "it could have been" and implies a stronger possibility than the following options.
* இருந்திருக்கக்கூடும் (irundhIrukkaKoodum) - Similar to the above but with a slightly weaker possibility.
More idiomatic:
* நிச்சயமா இல்ல (nichchayama illa) - This means "not certain" and hints at the possibility of something happening but without strong evidence.
* அப்படி இருந்திருக்க வாய்ப்பு இருக்கு (appadi irundhIrukka vaayppu irukku) - This means "there is a chance it could have been like that" and emphasizes the possibility.
* என்னவோ இல்ல (ennAvO illa) - This is a casual expression meaning "who knows" or "maybe" and implies uncertainty.
Using verbs:
You can also use verbs to convey the idea of "might have been":
* சாத்தியம் (saathiyam) - "possibility"
* நிகழ்ந்திருக்கலாம் (nigazhnthIrukkaLam) - "might have happened"
* நடந்திருக்கலாம் (nadandhIrukkaLam) - "might have taken place"
The best way to translate "might have been" depends on the specific situation and the level of certainty you want to express. Consider the context and choose the phrase that best conveys the intended meaning.