"Just as DNA examiners can point to repeating base pair matches to justify an identification, image examiners must be able to point to actual physical features on a face or body to justify their conclusions in court,” an FBI publication from 2008 read.

A bank robbery trial 16 years ago was a watershed for such testimony. Prosecutors charged an ex-convict with robbing a string of banks across South Florida over two years. Richard Vorder Bruegge, an FBI image examiner, told jurors that the button-down plaid shirt found in the defendant’s house was the exact shirt on the robber in black-and-white surveillance pictures. The examiner said he matched lines in the shirt patterns at eight points along the seams.

The prosecutor asked Vorder Bruegge what were “the odds in which two shirts would be randomly manufactured by the company, having all those eight points of identification lining up exactly the same?”

Only 1 in 650 billion shirts would randomly match so precisely, Vorder Bruegge said, “give or take a few billion." . . .

The statistics were also preposterous, seven statisticians and independent forensic scientists told ProPublica.

The features Vorder Bruegge matched might be common in plaid shirts, making them of little value for identifying the garment, said Karen Kafadar, chair of the statistics department at the University of Virginia. No one has studied the alignment of lines on men’s button-down shirts. There is no database of shirt features allowing Vorder Bruegge to calculate the probability of a random match, a statistic used to explain results from DNA typing.

Kafadar has worked in forensic science validation for the past two decades, contributing to a groundbreaking study of the FBI’s bullet lead analysis. She said Vorder Bruegge’s statements are brazen.

“Somehow they feel perfectly entitled to make outrageous statements,” said Kafadar, who said the 1-in-650-billion claim “makes about as much sense as the statement two plus two equals five.”