After graduating from
Rutgers Law School in 1931, Nelson had killed two FBI agents prior to fleeing the scene, wounded, and later died at his wife's side. The FBI, unaware of Nelson's death, continued a broad search for him, which included several home raids, through the night and into the following day. The search was not called off until a tip led them to Nelson's body, which was lying in a ditch in what is now
Skokie, Illinois. Walsh was on the team that tracked criminal
Arthur Barker, son of gangster
Ma Barker, to
Chicago in 1935. A subsequent search of Arthur's apartment revealed information that eventually led to locating other members of the Barker family. Walsh was later involved in the tracking down of
Public Enemy Number One
Al Brady in 1937. On October 12 of that year, he was with a group of FBI agents who ambushed Brady’s gang at Dakin’s, a
Bangor, Maine sporting goods store. Warned by the store owner that some men was wanting to purchase some Thompson submachine guns and would be returning in a few days to collect them, the FBI believing them to be Brady and his gang decided to set a trap. The gang’s car drew up at 8:30 a.m. and when Brady Gang member James Dalhover entered the store he was apprehended by Walsh and taken to the back by other agents. As Dalhover was being interrogated, Brady and another gang member, Clarence Lee Shaffer, Jr., emerged from their parked car with guns in their hands. Walsh was approaching the front of the store with a gun in each hand. Upon reaching the glass front door he saw Shaffer looking though it at him. Both men fired simultaneously through the glass. Mortally wounded Shaffer collapsed to the sidewalk, while Walsh had been shot in his right hand and into his chest. Despite this he stepped outside firing with the gun in his left hand at Brady, who was still moving after having already been hit by the other law enforcement officers. Brady was killed. ==World War II==