Two (A planet) can keep a secret if one is already dead (framed)
Alright, buckled up im gonna ruffle some of your feathers. Okay but do you recall Spock's famous quote: "The needs of the many outweigh the needs of the few"? And if you are one of the older Trekkie, you remember how Spock desperately attempted to conceal Pon Farr and its existence? How repressed Vulcans are? I raise you, what if we take this further onto a different, darker path.
Say, lets move aside from starship and Starfleet and Federation for a moment. Focus on a normal, average city in the future where human and aliens mingle in their daily life to life.
Imagine a Vulcan and Human's friendship. It's not hard. Despite some of the xenophobic tendencies from both races, there are good and kind people still. This Vulcan is of minor nobility (or the revelant of one) while the Human is your typical office worker of some kind. They meet at the workplace. Friendship strikes. And at some point, something deeper lurks at the end of the string.
However, due to whatever reasons the Vulcan cannot get to their planet and bondmate in time to relieve of the mating urges and the Human, their friend and possibly something more, is closeby.
A pure blooded Vulcan is more affected by Pon Farr fever and is more aggressive for it. The Human, confused and scared, defended themselves.
They succeed but the Vulcan is dead.
It's the nightmare of every Federation. So was the Vulcan once they got the hint of what occurred.
The Vulcan council cannot allow Pon Farr to become public knowledge. Think about how other races would treat them afterwards. Their austere, logical demeanor: gone in a second. Reduced to animals who can't control their base insticts. They cannot allow this one incident to affect the whole race. So the decision is born.
They blame the Human. Go full out. Scrutinize the Human's past for every single inconsequent flaw that can be used against them. Vulcans are patient. And if there is none? Well, fabricate evidence. Not the hardest thing they have done. They accuse the Human of having tampered the drink, intent to subdue the Vulcan but the latter fights back, resulting their death.
The Human is trapped in an endless cycle of nightmare. First, their friend seemingly for no reason attacked and tried to force them who is now dead by the Human's own hands. They were relentlessly questioned and investigated. Their life became public's amusement playground. Evidents seemingly pops up from out of nowhere pointing to them having already planned for this, that they were the one to start the altercation in the first place. No one believes in their innocence: not their their family, friends, coworkers or officers handling their case. None.