Upon focusing their investigation into missing persons from the Lancashire area, the memory of the Chief Constable of Dumfriesshire was triggered: he had read just days earlier in Scotland's Daily Record newspaper of the disappearance of a 20-year-old woman from Lancaster named Mary Jane Rogerson. Rogerson was employed as a nursemaid to the three children of a 36-year-old Parsee Indian doctor named Buck Ruxton. Ruxton lived in Dalton Square, Lancaster. On 9 October, the Chief Constable of Dunfriesshire contacted Lancaster Borough Police, relaying his strong suspicions as to who one of the two dismembered bodies may indeed be.
The distance (some 110 miles) the dismembered human remains were transported.
Mary Rogerson was, by all accounts given by her family, a friendly, simple girl who had never gone missing prior to her disappearance on or around 15 September, 1935. Dr. Ruxton had only gone to police and reported his wife and nursemaid missing on 4 October upon the insistence of Miss Rogerson's father and stepmother. The Rogersons were extremely concerned at not having heard from their daughter for three weeks, and in an obvious attempt to allay their increasing concern for Mary Jane's safety, Dr. Ruxton had spun fabrications to the parents about Mary being pregnant and his wife travelling with her to terminate the pregnancy.
Acting upon the likelihood one of the bodies may be that of Mary Jane Rogerson and learning that Dr. Ruxton's wife, Isaballa, had not been heard from since the evening of 14 September (when she had returned to Lancaster from a visit to her 2 sisters in nearby Blackpool), the stepmother of the girl was called in to see whether she could identify any pieces of clothing used to wrap the bodies. The stepmother was able to identify a blouse which had been used to wrap one of the pieces of flesh found at Moffat as being the same blouse to which she had given her stepdaughter. She ws able to conclusively confirm this by stating the repair work done upon one arm of the blouse was performed by herslf to patch a small hole in the elbow. A pair of child's shorts were also named by the stepmother, Jessie Rogerson, as being passed onto Dr. Buck Ruxton's wife by a woman who had lodged with the Ruxton family in June of that year (the woman in question later verified this; even describing a distinctive knot she had tied in the elastic of the shorts which was still in place upon their discovery).
At this point the Dumfriesshire police handed the overall control of the investigation into the discoveries (which was headline news across Scotland and England) to the Chief Constable of Lancaster, a Captain Vann.
Astonishingly, on the eve of his being called to the polce station, Dr. Ruxton had himself visited the same police station of his own volition, in possession of a copy of the Daily Express newspaper, demanding to see the Chief Constable. When he was invited into Captain Vann's office, he asked the officer: "Can't you do something about these news reports?" Ruxton explained that some community gossip was linking him to the murders as his wife and nursemaid were missing and his reputation and medical practice was suffering as a result. He then gestured to an article in the newspaper he was carrying, adding "This newspaper says that this woman has a full set of teeth and I know of my own knowledge that Mary Rogerson has at least four teeth missing from her lower jaw. Can you publish it in the papers that there is no connection between the two and stop all this trouble?" He also asked that enquiries be made to find his wife, Isabella.
Vann later stated that as he talked, he became more exasperated and the following morning (12 October), he was called to answer further questions. His replies to specific questions were evasive and contradictory. At 7 a.m. the day after he was called to, Vann informed him that "You are formally charged that, between 14 and 29 September, 1935, you did feloniously and with malice aforethought murder one Mary Jane Rogerson."
Ruxton's reply was on the defensive; giving an incredulous look at Constable Vann, he replied: "Most emphatically not - of course not! The farthest thing from my mind. What motive and why? What are you talking?"