On 5 March 1879, a box was discovered near Barnes, upon the banks of the Thames. It contained human fragments, severed from the trunk. During the searches that followed, the police found burnt bone fragments, tools, and sundry traces within the Richmond house from which Mrs Thomas had vanished. At the trial, the medical men could not say how the woman had met her death; they were able, however, to describe what had been done to her body. The inquiry led the jurors back to 2, Vine Cottages, where Kate Webster had resided in the service of Julia Martha Thomas, and thence to a box borne through the night onto Richmond Bridge.
Mrs Thomas resided in Richmond and let rooms in her house. Webster had entered her service in late January or early February 1879. When she reappeared in early March, she introduced herself to the neighbours as "Mrs Thomas," a widow who had just inherited a comfortable house in Richmond. Her father, she declared, was calling her home to Ireland; it was necessary to dispose of the furniture before her departure. She requested Henry Porter, a former neighbour, to find her a broker. At the public-house, she showed him five small rings and several photographs, which she represented as those of her father and of her deceased sister, objects she claimed to hold from her family. Her story lacked neither furnishings, nor a departure, nor family papers; it included also a six-year-old boy whom Webster presently placed in the care of Porter’s wife.
The last witnesses to have seen Mrs Thomas alive placed the encounter at the end of February and the beginning of March. A young neighbour, Julia Nicholls, met her on the Sunday evening at the entrance to their place of worship. Mrs Thomas appeared agitated and withdrew before the conclusion of the service. Elizabeth Ives, her next-door neighbour in Richmond, saw her gardening on Saturday, 1 March. Thereafter, inquiries made at the house met with contradictory replies. Webster stated that her mistress had gone out; presently she announced that she had sold the house and its furnishings. Mary Roberts, who had called to speak of a repair to the roof, heard her answer that the leak had ceased; Webster added that they were cleaning the premises in anticipation of visitors that evening. The neighbours heard sounds of movement, saw chattels being carried away, and observed that the card advertising "apartments to let" had been removed.
The weightiest piece of evidence in the inquiry was a box secured with a cord. In his testimony, Robert Porter recounted that Webster had met him and his father, then took him with her to Richmond. At the house, she asked him to assist in carrying a box to the bridge. She purported to have an appointment to meet a friend there. The box was already prepared, shut, and bound twice round with cord. Porter took hold of one side, Webster the other. Upon reaching the last recess of the bridge, she bade him go on alone: her friend was to join her there. As he walked away, he heard a slight splashing noise. He could not say whether it arose from the box or from a barge beneath the bridge. Webster overtook him without the box, telling him that she had seen her friend.
Robert did not understand at the time what he had just carried. The hour was late, the last train had departed, and Webster offered him a bed at the house. The lad related having passed the night in a room above the side door; he set out the next morning for Hammersmith with a bag of provisions. He said nothing of the box to his mother until he read in a newspaper that a chest containing human remains had been found in the river. He then told her that the box described answered to the one he had carried; he had already spoken of the incident to John Church.
At the mortuary, James Adams described a portion of the thigh as being still fresh, whilst other fragments were altered by water or chemical agents. Frederick Bond, called upon to examine the remains, described bones sawn through without regard to the joints, and parts of the flesh boiled. He matched in particular a leg and a thigh whose articular surfaces corresponded; the head was wanting. Adams had initially estimated that the victim might be under thirty years of age; Bond maintained that she was above fifty. At the trial, Adams concurred in an estimate of over fifty years, while acknowledging that the remains did not permit of a precise measurement. Neither of the surgeons could determine whether death had been natural or violent.
The police searched 2, Mayfield Cottages, at Richmond, also known as Vine Cottages. In the ashes beneath a grate, Inspector Pearman gathered up charred bones and buttons. He also discovered a chopper in the coal cellar, a razor, a torn nightdress, a lantern, and, under the sink, the handle of a box which fitted the chest recovered from the river. Cord of the same description lay near at hand. Upon the woodwork of a bedchamber, the paper of a staircase, and the wall of the larder, Pearman detected stains which Bond identified as mammalian blood; he was unable to determine its origin. In the copper boiler in the kitchen, he discovered a black fatty substance and calcined fragments.
Meanwhile, Webster had been selling the furniture. She had brought Henry Porter to Richmond to show him over the house, had asked him to find a purchaser, and, together with John Church, had appraised the effects at sixty-eight pounds. Church provided a note for this sum, but the receipt produced at trial was unsigned. On 18 March, when Miss Ives made inquiries concerning the landlady, Webster went upstairs to fetch some dresses and a fur-lined cloak, then departed the house. The carmen presently brought back the furniture they had just removed. In the ensuing days, Church and Porter helped gather together what remained; Webster had already dispatched linen and plate to Church’s premises.
Apprehended in Ireland at the end of the month, Webster was brought back to England. Aboard the vessel, she asked whether anyone was already in custody for the murder, declaring that an innocent person ought not to suffer for the guilty. In her first statement, she accused Church: she alleged that he had strangled Mrs Thomas, threatened her with a knife, and compelled her to transport the box. She admitted to having helped remove the goods, but denied having slain her mistress. Subsequently, she introduced Henry Porter’s presence in the house into her narrative, attributing to Church and Porter various conversations regarding the sale of the effects and the falsehoods to be told to the neighbours.
The other witnesses disputed several of the scenes related by Webster. Robert Porter confirmed the carrying of the box and the splash, but assigned the episode to a different day from that given in her statement. Elizabeth Ives denied that Webster had ever tendered her the rent or that she had refused the money. Maria Church denied having seen Webster at daybreak on 4 March, rejecting the scene in which Porter was said to have waited for her husband. In open court, her accusations against Church and Porter were thus confronted with their denials, with the articles recovered from the houses, and with the account of the box upon the bridge.
At the close of the trial, the jury returned a verdict finding Kate Webster guilty. When called upon to receive her sentence, she pleaded pregnancy. A jury of matrons heard evidence from a female warder of Newgate and from Mr Bond, the surgeon, who had examined Webster; they found that she was not "quick with child." Mr Justice Hawkins thereupon pronounced sentence of death.