He achieved notoriety in 1798 when tried and acquitted by his peers in the Irish House of Lords for murder of his nephew Henry Fitzgerald.

He was the eldest surviving son of Edward King, 1st Earl of Kingston and Jane Caulfeild.

On 18 May 1798, he was tried by his peers in the Irish House of Lords after allegedly murdering his nephew Colonel Henry Gerald FitzGerald.

FitzGerald was a married man who eloped with King's daughter Mary, and had submitted to an inconclusive duel with her brother Robert.

Public sympathy was on King's side and when after three summonses no witnesses came forward he was acquitted.