On 4 March 1966, Clarence Greenwood was found deceased in a bed at his mother’s home at Drayton Street, Bowden.
A post mortem examination found that the 40-year old died from the effects of arsenic poisoning.
Mr Greenwood is believed to have drunk from bottles of contaminated beer and stout purchased by his brother Frank.
Frank was also violently ill after drinking from the bottles, but he survived.
It appears the bottles were deliberately contaminated with arsenic.
A reward of up to $200,000 is on offer for information that leads to a conviction in this case.