The Great Train Robbery

 The Great Train Robbery took place on 8 August 1963. It was a notorious crime where the robbers held up a train and stole a vast amount of money. This YouTube video explains it all. 

Martha Tabram

 On 7 August 1888 Martha Tabram was murdered in the East End of London. The unfortunate woman was stabbed repeatedly. Some people think she was the first victim of the notorious serial killer Jack the Ripper. 

Last woman executed in Sweden

 On 7 August 1890, Anna Mansdotter became the last woman to be executed in Sweden. She was convicted of killing her daughter-in-law. She was beheaded with an axe.

The First Man Executed in the Electric Chair

 On 6 August 1890, William Kemmler became the first man to be executed in the electric chair. The first woman executed in the electric chair was Martha Place in 1899.

Dr William Palmer

 The famous Staffordshire poisoner William Palmer was born on 6 August 1824. In 1856 Palmer was convicted of poisoning his friend with strychnine and sentenced to death. On the gallows, he is supposed to have said 'are you sure this damn thing's safe?' (a very doubtful story!) Palmer was dubbed 'The Prince of Poisoners' and is believed to have poisoned up to 15 people.

The Narborough Murders

 I found a good video about the infamous child killer Colin Pitchfork. It's a horrific case.

Dr Crippen - the first murderer caught by radio

 On 31 July 1910 Dr Crippen was arrested when arrived by ship in Canada. Hawley Harvey Crippen was believed to have murdered his wife, Cora Crippen by poisoning her with hyoscine. Police became suspicious when she disappeared and Crippen fled with his lover, Ethlel le Neve to Canada. A human torso was found in his cellar, but the head and limbs were never found. The captain of the ship Crippen and le Neve were on became suspicious of the pair, who were, of course travelling under false identities. Ethel le Neve was dressed as a boy and they supposed to be father and son. However, the captain was not fooled. He radioed London. Police sailed for Canada on a faster ship and arrived before Crippen. Dr Crippen and Ethel le Neve were returned to Britain for trial. 

Hawley Harvey Crippen was convicted of murder and he was hanged on 23 November 1910. Ethel le Neve was tried separately and she was acquitted. Dr Crippen became famous as he was the first murderer caught by radio. However, some people now question if Dr Crippen really murdered his wife. Was the torso in the cellar really that of his wife? Was Dr Crippen innocent of his wife's murder? - BBC News