Very little is known about Sergeant Leach aside from some mentions in the contemporary press. All that is known is that he was a Sergeant in Scotland Yard who served in H division. He, along with Detective Sergeant Thick and other police officers, was among the first to respond to the scene of Annie Chapman's murder at 29 Hanbury Street. They arrived at the scene around 7:00 on the morning of September 8th, 1888.
The only other mention of him in official documents is from a year later, when he was involved in the apprehension of a fraudster, Edwin Smith. He appeared in the Old Bailey to give testimony on the matter on the 4th of February, 1889. No other documentation exists of his life.