Mystery surrounds the case of a teenage mother who dumped her infant daughter in a Hampshire river.

It was, as the judge observed, an extraordinary case.

Though regarded as a natural, affectionate mother, Eliza Froud dumped her infant daughter in a Hampshire river. Why? Was it because, as the teenager claimed, she had died from bronchitis, or was it murder as a letter to her own mother indicated?

The 17-year-old lived with her mother in Southampton where she was employed as a maid. Mild-faced and good looking, she felt more comfortable in seeking the company of children rather than those of her age. Naive, she was easily seduced and fell pregnant.

To avoid her family's good name being besmirched, she returned to their home town of Andover where she entered the Union Workhouse to have her illegitimate baby. Within weeks on April 4, 1880, she was delivered of a healthy and well-nourished girl to whom she was apparently very loving.

Eliza was intent on returning to Southampton and five weeks later on May 11 prepared to leave. The matron saw the baby wrapped in her mother's jacket, and as a kind gesture, lent her a shawl. The teenager then left the workhouse to register the birth of the baby she christened Ellen. The registrar saw she had "a bundle" in her arms but it did not move and she told him she had about 20 minutes to reach the station for the 12.40pm service.

In the next three hours, Ellen - alive or dead - mysteriously disappeared, a fact four witnesses corroborated, and Eliza did not reach the station until 5pm.

At 3.45pm, she encountered the matron and her husband who naturally were somewhat puzzled she no longer had the baby with her and was still In Andover. "Haven't you gone yet, Eliza?" he rhetorically asked. Strangely, she did not answer and walked off.

At 4.15, she was met by a young workhouse resident returning from school who was anxious to see the baby. "I've left her with another person in town," she explained, and thrusting the shawl, which was "wringing wet," to her, again walked off.

At 5pm, she finally arrived at the station where a widow was anxious to know of the baby's progress. She was stunned by the reply - "it's dead," she muttered.

The elderly woman was aghast. "Dead! I heard you had one but I had not heard of its death. When did it die? How old was it?

"Five weeks all but three days."

The teenager was clutching a head whittle which she had intended to throw over the wall as it was no longer of any use, but instead gave it to the elderly woman who noticed her boots and dress were saturated.

At that point, the Southampton train steamed into the station and Froud boarded it.

The child's disappearance prompted a police investigation and on May 22, detective Lawler interviewed the tearful teenager at her mother's home. He warned he might have to take her in custody on suspicion of murder and after she made no reply, told her to get some clothes together. She and her mother left the room for about 20 minutes and when they returned, her mother told the police officer Eliza had confessed to her she had put the baby into the River Anton.

"Where?" he asked.

"In Barlow's Lane," she replied.

Ironically, as they were speaking, Ellen's corpse had just been found by a miller lying in mud in a side stream.

On July 5, Eliza appeared at Hampshire Assizes in front of Mr Justice Grove, charged with murder. The prosecution was represented by Mr Ravenhill who told jurors of her maternal instincts. "But on the other hand, I must remind you that a letter written to the defendant to her mother showed a premeditation to put away the child, and if I can prove that, I fear that whatever your sympathies with the defendant in her unfortunate position, it will be your duty to find her guilty."

Eliza's mother, Mary Ann Froud, was the first to give evidence, confirming she had received two letter from her daughter, the first a week after the baby's birth and the second saying she was returning to her home in Southampton but alone. Ellen, she said, "was gone."

After she had arrived, Mrs Froud asked her when the baby had died. "She replied on the Friday before and was buried on the Monday, and that it died from bronchitis in the Union. When the police came, Eliza said she would tell the truth about it, that she had died and put it in the water at Barlow's Lane."

Mrs Froud made it clear she would have welcomed her back with or without the baby, rejecting with tears streaming down her face that Eliza was a murderer. "She is a good and affectionate girl and always very fond of children."

When questioned why she had not produced the letters in court, she claimed she did not know where they had gone but thought her sister might have taken one.

Martha Littlecott, for whom Eliza had been working, described the Froud family as united and affectionate but suffered from ill-health. "They were always subject to very hard coughs in the winter. Eliza was very low and depressed after she came home, and I don't believe she was right in her mind."

Asked to elaborate, she replied: "She was always so simple in her ways. She appeared like a silly girl than one of seventeen. She would go out of doors and play with children and amuse herself with children's toys."

Crucial evidence came from Dr. Farr from Andover, who carried out a post-mortem on Ellen's decomposed body nearly a fortnight after she had disappeared, and undermined the prosecution's case by revealing he could not be certain of the cause of death.

"From its appearance, I imagine the child had been nursed for a short time before her death. I could not detect any marks of violence or any indications of bronchitis. My opinion is that the child died quickly and from some form of suffocation. It might have suffocated in the shawl or by something placed over its mouth, accidentally or otherwise, or being drowned or stunned in the process of it."

The judge, realising the importance of his evidence, bluntly asked: "What sort of weight can be placed on what you have said?" Farr, handicapped by the state of Ellen's body, replied: "Had the body not been decomposed, I would have expected to find traces of bronchitis if it had existed."

In his closing speech on behalf of Eliza, barrister Mr Warry said there was no evidence of malice by the defendant towards Ellen and no proof she was alive when put into the river. "Many of us as fathers will know the vicissitudes for which children of this tender are liable. Had she known she would have not have been welcome at home, there might have been some reason for killing the child but her mother said she would have welcomed her and her baby gladly. The case with the shawl has been overstrained, for the sending it back is not at all consistent with the theory she had killed her offspring and wished to conceal the fact. By returning the shawl, she had gone the right way to let all at the workhouse know what happened."

Urging jurors to put their feelings to one side and act purely on the facts, the judge said the absence of malice was a point in the defendant's favour but, on the other hand, no motive was sufficient for one person to kill another.

"If she put the child into the water believing it was dead, though she is guilty of criminal negligence in not taking steps to recover it, she is not guilty of murder. However, if the child had died in her arms, why did she put her in the water at all. Why did she not take it back to the workhouse and say it was dead. This case, look upon it as you like, is an extraordinary and peculiar one."

Jurors retired for about 10 minutes before acquitting Eliza, the foreman explaining there was no evidence to prove the baby was put into the river when it was alive.