Ambassador 1: Seeing Red by Patty Jansen

24 October 2114: the day that shocked the world.
Young diplomat Cory Wilson narrowly escapes death in the assassination of President Sirkonen. No one claims responsibility but there is no doubt that the attack is extraterrestrial.
Cory was meant to start work as a representative to Gamra, the galactic federation that governs the Faster Than Light transport network, but now his new job may well be scrapped in anger.
Worse, as Earth uses military force to stop any extraterrestrials coming or leaving the planet, as 200,000 extraterrestrial humans are trapped on Earth, as the largest army in the galaxy prepares to free them by force, only Cory has the experience, language skills and contacts to solve the crime.
But he faces a culture where looking a superior in the eye can get you killed. Never mind accusing him of murder.
A science fiction thriller.