Actually, it’s true. Eyewitnesses are regularly wrong. In fact, eyewitness testimony is the most often cited reason for all the wrong convictions which are later reversed by DNA tests. If you are interested in why this should be, check the web page on the subject (more precisely the links on the web page) by Gary Wells, a psychologist who’s done much of the original research on the subject. It’s at http://www.psychology.iastate.edu/~glwells//
Apparently we are much more suggestible than originally believed.