Underbelly, Miss Marple and the Sherlock Holmes movies starring Robert Downey jnr demonstrate the appetite for stories of miscreants from yesteryear and endeavours to bring them to justice.

It is better still when the stories are true, as is the case of The Mad Dentist of Wynyard Square. His bizarre story will take centre stage at Notorious Criminals – A Snapshot of Sinister Sydney, an exhibition opening this week.

It does not get much more sinister than the murderous actions of Henry Louis Bertrand, said to have been a mesmerist with the power to control others. His trial heard claims from several of his female patients, wondering if his attentions while they were in the dentist's chair had extended beyond the examination of teeth. So salacious were the details during his murder trial that the judge ordered them to be suppressed until proceedings were completed.

Bertrand, married with two children and considered a successful dentist, became entranced with one of his patients, Maria Kinder from St Leonards, who was also married, and they had an affair. The two couples knew each other socially and would meet to play cards.

Bertrand decided his lover's husband, Henry Kinder, a banker who liked a drink, might be better out of the way.

On three occasions he persuaded the male assistant at his dental practice to row with him across the harbour to spy on the Kinder household. On one occasion he blacked his face and carried a tomahawk.

Nerida Campbell, curator at the Justice and Police Museum, formerly the Water Police Court where Bertrand stood trial, said: "He then convinced his young assistant to help him purchase a pair of pistols. Bertrand decides he will dress as a woman while the assistant goes to the counter and buys the pistols. He then buys a large pig's head so he can practice firing."

At one of the social evenings at the Kinders', Bertrand and his wife, Jane, were all in the house when a shot was fired.

Mr Kinder sustained a serious head injury and the ladies did not know if he had shot himself or whether Bertrand was responsible.

A doctor arrived and was told Mr Kinder was suicidal. He survived so Bertrand decided to resort to poison, allegedly administered by Mrs Kinder. Mr Kinder died on October 2, 1865. The death was recorded as a suicide.

Ms Campbell added: "Ten days later Bertrand got a letter entitled 'Murder' from Mrs Kinder's ex-lover Francis Jackson, saying: 'I know you committed this murder. My conscience is troubling me, send me some money and I'll go away to New Zealand'."

Bertrand told police he was being blackmailed and Jackson was sentenced to 12 months hard labour.

Bertrand's behaviour became so erratic that he was locked up in the Darlinghurst Gaol in November that year and was finally arrested in relation to the murder. His wife and Mrs Kinder were charged as accessories.

"At the initial hearing, that's where the salacious details about the relationship came out," Ms Campbell said.

"After her husband was dead, Mrs Kinder moved into the Bertrands' house and the three of them shared a bed. He forced his wife to remain in bed while he had intimate relations, as they say, with Mrs Kinder.

"Mrs Bertrand got whipped by her husband, using his lover's riding crop, but still she didn't leave.

"The case had mesmerism, sex, poison and guns. It had everything you could want in a story."

After two trials, Bertrand was condemned to death for murder in February 1866, but the sentence was commuted to life and he served 28 years. The women walked free. Bertrand left Sydney on a steamer, destination unknown.

The exhibition, including other sinister stories, opens at the Justice and Police Museum on Saturday, October 18. Open Saturdays and Sundays only.