Update: We talked to the higher-up to get the full story. Several months ago, the minority employee questioned a decision of the higher-up which the higher-up perceived as insubordination (incidentally, two of his white coworkers were also involved in the same insubordination incident but they were not given a subsequent mid-year evaluation or later terminated).
The higher-up wanted to get rid of him but needed valid justification. The higher-up saw performance lapses and the minority employee was given a mid-year evaluation to shape up (with written feedback from the immediate supervisor and another manager). He was the only one to receive a mid-year evaluation, with no prior or subsequent written warning or documentation of feedback. There's no numerical scoring on a scale as with our annual performance review, no date, no mention of disciplinary consequences, no timeline and no signature from the supervisor, HR or any higher ups.
The way it was executed was very sloppy. From the advice given here it appears that the company is at significant risk for a racial discrimination suit as by coincidence he happened to be the only minority in the department. It seems the minority employee's immediate supervisor was just as fearful of incurring their wrath and went along with it for fear of being disciplined for insubordination as well.
For those whose suggestion is to terminate the higher-up, the higher-up has been with the company for less than a year (less time than the minority employee and immediate supervisor). The higher-up wasn't involved in hiring the minority employee. And isn't HR just as culpable in allowing this to proceed without adequate documentation and placing the company at legal risk?