Fascinating stuff - big black cats are one of those cryptid reports that absolutely refuse to go away no matter how many wildlife officials insist they don't exist outside South America.
Scotland's absolutely riddled with similar accounts. The Beast of Bushy type sightings happen practically on my doorstep in the Lothians, so I'm not dismissing you for a second. Three sightings in a month from the same witness is genuinely significant data - that's not misidentification, that's a pattern.
Few questions worth considering:
Size relative to known animals - people consistently underestimate cat size in the field. What are you comparing it against?, Movement - melanistic leopards and jaguars move distinctly differently from domestic or feral cats, almost liquid-like, Time of day - crepuscular sightings are more credible imo, that's when genuine apex predators are actually active
My usual approach would be to get some audio equipment out there - I use a Zoom H5 for EVP work but it's equally decent for wildlife monitoring - stick it near whatever terrain features it's using as a corridor and see what vocalisation you capture. A melanistic jaguar's contact call would genuinely make your hair stand on end.
Anyone else cross-referencing these Ozarks reports with livestock predation records from local agricultural offices? That's usually where the hard evidence eventually surfaces.