Green’s Dictionary of Slang

1. (UK Und.) to identify (and arrest).

1838		Mayo Constitution (FL) 25 Sept. 3/5: Maguire charges gregg with his folly, trickery, or temerity, and threatens to ‘show him up’.
1865		Leaves from Diary of Celebrated Burglar 89/1: It was often observed that while other ‘picking-up molls’ and their ‘blokes’ got occasionally ‘run in,’ neither Shad nor his ‘moll’ got ‘shown up’.

2. (US Und.) to put in an identification parade.

1851		‘Greenhorn’ [G. Thompson] Bristol Bill 48/1: the City Marshall took upon himself the responsibility of [...] ‘showing up’ the woman as one of a gang of thieves and counterfeiters [...] Bill stood perfectly at ease, [...] looking carelessly at the crowd before him.
1857		N.Y. Morning Express 5 Nov. 3/9: On Wednesday the Deputy Superintendent’s detectives brought in a dozen of the young scamps [i.e. pickpockets’ assistants] for the purpose of ‘showing them up.’.
1904		Salt Lake Herald (UT) 19 Oct. 5/1: He’s showed up to the other elbows and two wise to him as a gope cracker.

3. (UK Und.) to make a complaint against.

1885

M. Davitt Leaves from a Prison Diary I 49: He [...] applies to see the visiting director every month ‘to show up’ the warders for over-doing their duty.