Harvey Schlossberg, a former New York City traffic cop with a doctorate in psychology who choreographed what became a model law enforcement strategy for safely ending standoffs with hostage takers, died May 21 in Brooklyn. He was 85.

In a pioneering training film he made for the New York Police Department in 1973, Mr. Schlossberg said that in a hostage situation, police officers “all believed ‘If you give me the right gun with the right bullet, I can put everybody out.’” Instead, he counseled patience and “crisis intervention therapy.” Delaying tactics, he said, allowed more time for the criminals to make mistakes and, just as crucially, to develop a rapport with their victims, leaving the hostage takers less likely to harm them.