But prosecutors now say Detective Desormeau, 34, struggled with one aspect of police work: telling the truth. After relying on Detective Desormeau’s word in hundreds of cases, prosecutors no longer believe him credible. In two cases, prosecutors have accused Detective Desormeau and his partner of making up crucial details when arresting people, even testifying about criminal activity that may never have occurred. They have said they are reviewing some of his old cases, though how many is not clear.
The two detectives were indicted this year, adding to the body of evidence that police perjury and half-truths remain a persistent problem for the New York Police Department. And as more arrests and confrontations are being recorded, evidence of police falsehoods is more apparent.
The issue of false or misleading statements by the police has, on a national level, been intertwined with the issue of excessive force and the debate over whether officers are too quick to shoot people, particularly black men.
But the phenomenon of false or misleading police statements has not been confined to high-profile cases in which officers try to justify the use of deadly force. In New York, the practice of routinely making up facts to justify a dubious arrest was entrenched enough that it got its own nickname more than 20 years ago — “testilying.”
https://www.nytimes.com/2017/10/10/nyregion/he-excelled-as-a-detective-until-prosecutors-stopped-believing-him.html