Mr. Geberth, the former homicide detective, said the problems with trying to trick murder suspects had more to do with a detective’s need to maintain credibility in the courtroom than with fending off a challenge by defense attorneys. Generally, he said, his advice to detectives is, “You don’t make a false claim of evidence.” Nonetheless, he said, ruses were often necessary during interrogations of murder suspects, who often cling to false accounts or alibis. “I believe in trickery and deceit unless you are making an innocent person confess,” he said. “Most people who are charged with homicide probably did it.” But Mr. Saltzburg said detectives and other police officials were sometimes swayed too much by the limited evidence that is available to them and by the belief that the person under suspicion must be guilty. “Even after cases are cleared by DNA, it is not uncommon for a detective to say, ‘I know he did it,’” Mr. Saltzburg said. “They are true believers.” So much for a presumption of innocence. Not to mention those statements are complete nonsense together. From a a NY Times article entitled Detectives’ Interrogation Tricks Under Scrutiny After Court Ruling