Green’s Dictionary of Slang

1. (US Und.) put in prison for a non-specific length of time, usu. a very long or life sentence.

1904		Number 1500 Life In Sing Sing 246: Buried. Convicted.
1935		A.J. Pollock Und. Speaks 16/1: Buried in prison, to be imprisoned for a long term (prison).
1960, 1975		Wentworth & Flexner DAS.
1967		P. Thomas Down These Mean Streets (1970) 314: The car stopped in front of a tall gray building, the Bronx Tombs. I was going to be buried again.
1992		Bentley & Corbett Prison Sl. 18: Buried An inmate with a life sentence. Buried may also be used to indicate a long prison sentence, usually 20 years or more.

2. (orig. US black) extremely drunk.

1927		‘Sl. Expressions for Drunk’ in New Republic in AS XVI:1 (1941) 9 Mar. 70: [...] buried.
1960, 1975		(ref. to 1920s) Wentworth & Flexner DAS.

3. (US Und.) held incommunicado.

1935		A.J. Pollock Und. Speaks n.p.: Buried, to be held incommunicado by the police.
1949		Monteleone Criminal Sl. (rev. edn).