INDIANAPOLIS, Ind. (Feb. 19, 2016)-- In many ways, he’s the perfect witness. A man who we will call “Alex” was an eyewitness to not one, but two murders that happened right in front of him.
One happened four years ago on the Northside of Indianapolis. Alex was driving home when a man was chased out of a nearby house and shot to death right before his eyes on the side of the road.
"He looked me dead in the eyes as he shot him four times, not even a care in the world," said Alex.
Alex watched as the suspect gunned down another victim who had also been chased out of that house.
"All I could do was stop and pray that nothing else would happen," he said.
The suspect escaped and the case remains open to this day. But Alex was able to give police a rare first person account of what had happened.
“People are asking you and questioning you, you're mind is like 'Did that really happen?' and you actually question yourself and you shouldn't."
Eyewitness testimony is the gold standard of evidence in the state of Indiana. It carries enough weight that prosecutors can get a conviction without much else. Prosecutors say they often build up their case with circumstantial and forensic evidence, but nothing replaces a good eyewitness.
"Anytime you have an eyewitness who's able to come in an provide a great deal of detail about what took place and they come across as credible and they've told the truth, that's how we figure things out in life and it’s no different in the courtroom, " said Deputy Prosecutor Ryan Mears.
But experts like Dr. Tracey Gunter say you might be surprised how the brain and its memory function works. The clinical and forensic psychiatrist is based at the IU Health Neuroscience Center. She teaches an entire course on neuroscience and the law. Dr. Gunter says when it comes to eyewitnesses, what they see is not necessarily what you get.
"Many times people think their brains act as a video recorder or a static camera even and have the idea this event is stuck in their brain somewhere," said Dr. Gunter.
Research shows memories stored in the human brain evolve and change over time. It happens even when that witness is certain that their memory of an event has never changed.
"We tend to believe if they can tell the same story over and over again that they are more likely to tell a factional truth and those things are in fact not true," said Dr. Gunter.
Prosecutors say they work closely with police to make sure every witness gives an accurate account in every criminal case. They contend that’s why they are willing to rely on such testimony so heavily.
"The most important thing to us is that they're telling the truth and so there's a lot of scrutiny in eyewitness testimony so that when you get to the trial process we're confident in the identifications,” said Mears.
For his part, Alex says the memory of witnessing a murder will stay etched in his mind. He still hopes that memory will someday close the case.
"It's always good to give as much information as possible, anything helps,” he said.