By John Ostapkovich

PHILADELPHIA (CBS) – Philadelphia police say they are 100 percent sure that they have the right suspects in custody in the beating death of Kevin Kless earlier this month near Independence Mall (see related story). But initial descriptions were way off.

The initial descriptions of the suspects and of the car were both wrong, but that doesn’t surprise Jules Epstein, Associate Professor of criminal law at Widener University.

Widener University Professor Jules Epstein. (Credit: Widener University)

The quality of eyewitnesses varies a lot, “sometimes eyewitnesses get it tremendously accurate. In the case you’ve described, there are a number of possible explanations. The simplest of which: it was night time. There’s some pretty strong research that the greater the stress of the event, the more the memory can be inaccurate.”

He says police have come a long way in sifting out the bad information. Also, hard facts are usually trump cards, “many of the early DNA cases are cases where a witness says it was John who did it but DNA showed it was Alex who did it. There was no problem prosecuting those people even though the eyewitness was dead wrong.”

Professor Epstein expects Philadelphia police have other solid evidence where eyewitnesses were wobbly.