The real question is whether one witness can prove, beyond a reasonable doubt, that someone committed the crime.
The answer is yes.
To give an unpleasant (but true) example, when I was in the District Attorney's office we had a rape case. The evidence consisted solely of the testimony of the victim. There was no DNA, no fingerprints, no physical evidence. There was no evidence other than her eyewitness testimony describing the rapist.
Can that be enough? Absolutely… if it is believed by the jury.
In this case, the victim testified the rapist had “Bitch Switch “tattooed on his penis.
He did.
While this is a dramatic example, it's not far different from an eyewitness identifying someone saying that they had any particular set of features whether it's deep-set eyes, facial hair, scar, a particular height or weight or other things. If the jury is convinced beyond a reasonable doubt that the accuser is identifying the "right guy" there is nothing preventing that jury from finding the person
