Green’s Dictionary of Slang

1. to hang, to choke to death.

a.1661		‘The Second Part’ Rump Poems and Songs (1662) I 163: That it please thee to assist / Our Agitators, and their List, / And Hemp them with a gentle twist.
1682		‘The Assembly of Modern Divines’ in Ebsworth Roxburghe Ballads (1885) V:1 182: There’s Johnson the Apostate, who deserves to be hemp’d.
1857		T.H. Gladstone Englishman in Kansas 264: This infernal scoundrel will have to be hemped yet.
1881		Trumble Sl. Dict. (1890).
1885		L.W. Spring Kansas 50: Some talked of ‘hemping’ the scoundrel, while others felt more like ‘cutting his throat’.

2. to garrotte in order to rob.

1859

Matsell Vocabulum 41: hemp the flat Choke the fool.