Why We Should be Skeptical When We Hear: ‘Police Release Sketch of Suspect’

09.21.16 By Innocence Staff

Why We Should be Skeptical When We Hear: ‘Police Release Sketch of Suspect’

Eyewitness misidentification in criminal investigations is the leading contributing factor in the 344 wrongful conviction cases overturned through DNA evidence in the United States. In addition to police lineups, composite sketches are commonly used to identify suspects. But as Karen Newirth, senior attorney at the Innocence Project and expert in eyewitness identification, explained to American Public Media (APM), these memory-based drawings can become roadblocks to productive investigations and implicate innocent people in the process.

Police say that composites are useful tools that can develop leads as well as rule out individuals previously thought to be involved in cases. But according to Newirth, composite sketches are too risky to offer any reliable value to law enforcement’s effort to get actual criminals off the streets. The drawings are too subjective. They’re based on memories, which are faulty and can be manipulated by various factors, and they rely on people’s ability to accurately convey in words what a particular face looks like.

For this reason, investigations can go awry when they’re based on the faulty nature of composites.

“We know that composites are a problem for innocent suspects and therefore a problem for investigations,” Newirth said. “The possibility of an innocent person getting caught up in an investigation as a result of having the misfortune of looking like a composite, or that somebody thought he looked like a composite, is very great.”

In addition to innocent people being implicated for crimes in which they’re not involved, creating composites can hinder a witness’s actual memory of the event.

“There’s been a significant amount of scientific research into composites,” Newirth explained.    “ . . . [T]he act of creating a composite can essentially contaminate a witness’ memory so that the witness can no longer discern, or has a very difficult time discerning, between their memory of the perpetrator and the likeness that they helped to create through the composite sketch process.”

Given all the science and the wrongful convictions to back up the data—composite sketches played a role in 30 percent wrongful convictions overturned by DNA—Newirth has a recommendation for law enforcement: “Although composites have long been a tool of investigation, they should be avoided at all costs.”

Learn more about eyewitness misidentification

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