Not only do people regularly confess to crimes they did not commit, they sometimes do so using details that, it is then asserted in court, they could only have known if they had been the criminal. They learn those details from the police in the course of their interrogations:
But more than 40 others have given confessions since 1976 that DNA evidence later showed were false, according to records compiled by Brandon L. Garrett, a professor at the University of Virginia School of Law. Experts have long known that some kinds of people — including the mentally impaired, the mentally ill, the young and the easily led — are the likeliest to be induced to confess. There are also people like Mr. Lowery, who says he was just pressed beyond endurance by persistent interrogators. . . .
New research shows how people who were apparently uninvolved in a crime could provide such a detailed account of what occurred, allowing prosecutors to claim that only the defendant could have committed the crime.
Professor Garrett said he was surprised by the complexity of the confessions he studied. “I expected, and think people intuitively think, that a false confession would look flimsy,” like someone saying simply, “I did it,” he said.
Instead, he said, “almost all of these confessions looked uncannily reliable,” rich in telling detail that almost inevitably had to come from the police. “I had known that in a couple of these cases, contamination could have occurred,” he said, using a term in police circles for introducing facts into the interrogation process. “I didn’t expect to see that almost all of them had been contaminated.”