Thain was a thirty-four year old constable from Suffolk who seven years previously had been a police officer on the Woolwich docks. His beat on Friday 31 August 1888 was a thirty minute circuit which took him along Brady Street, passing the corner leading into Buck’s Row. He did see “one or two” workmen walking along Brady Street. At about a quarter to four in the morning he was alerted by PC John Neil (97J, Bethnal Green), who was in Buck’s Row as he passed, to the presence there of the body of a dead woman. Shortly after joining Neil the two were joined by PC Jonas Mizen (56H, Whitechapel) who had been informed that a woman was lying on the road by Charles Allen Lechmere (who gave his name as ‘Cross’ at the inquest) and Robert Paul. Neil dispatched Mizen to Bethnal Green Police Station for the police ambulance, and Thain to bring Dr. Llewellyn from his surgery on the Whitechapel Road. Thain returned with the doctor about ten minutes later to discover that PC Neil had been joined by two workmen at the body.
Once the doctor had conducted an examination of the body at the scene he instructed that the body be removed to the mortuary. John Thain assisted the other officers in lifting the body from the road and placing onto the ambulance. In the process of doing this Thain discovered that the back of the body was saturated in blood, and he got blood on his own hands at this point. Thain did not go with the ambulance to the mortuary but kept watch at the place where the body was discovered until the arrival of Inspector John Thomas Spratling (J Division, Bethnal Green). Shortly following the arrival of Spratling Thain began a search of the surrounding area but uncovered nothing suspicious. We know that Inspector Spratling made his way to the mortuary to examine the body of the deceased.