He was a police officer for nearly 29 years, interrupted by a stint in the Marine Corps during World War II. Mr. Stein had served in China before the war and joined the police department a month before the attack on Pearl Harbor.

He re-enlisted in the Marines in February 1942 and served in the Pacific Theater, including the battles of Guadalcanal and Okinawa. He returned to his police job in October 1945.

“He told me that nothing in his police years was as harrowing as the war,” said John Vollmann, a retired police sergeant six decades Mr. Stein’s junior who befriended Mr. Stein through a mutual interest in department history.

“Mel told me that when he got to the bank, his Marine Corps experience kicked in,” Vollmann said. “He saw the (robber) with a sawed-off shotgun and got into a crouch. Buckshot flew over his head. Mel’s training saved him and the day.”

On the day of the robbery, Mr. Stein was in a patrol car with Cpl. Robert Heitz at Shaw Boulevard and Kingshighway, near the bank. The robbers, all from the Chicago area, rushed into the lobby at 10:19 a.m. Two tellers deftly tripped silent alarms.