It was stated in the press conference that the sketch was a composite of information that came from various sources, not just eyewitnesses. It was not specifically stated that the "she" (or "the person") who said "no blue eyes" was actually an eyewitness. "She" could well have been a forensic science lab technician who wrote the report on the DNA test results.
This was a very difficult presser to follow, as those who have watched it might agree. It was confusing, especially when Sargeant Riley seemed to inadvertently say "she" more than once when describing the source behind the physical features of the sketch. When I watched the press conference live, I thought he was describing the interpretations of the sketch artist, but in rewatching, it's hard to tell if that's who he is referring. The media are attributing it to an actual eye witness.