A Bihar court rejected the bail application of Manorama Devi, a suspended Janata Dal-United MLA and mother of murder accused Rocky Yadav, officials said.
Manorama's son Rocky is main accused in the killing a Class 12 student Aditya Sachdeva.
She is lodged in the Gaya Central Jail after she surrendered in a local court, which remanded her in 14-day judicial custody.
An arrest warrant was issued couple of days back against Manorama for keeping liquor in her home in Gaya town in violation of the prohibition law of the state and for harbouring her fugitive son who has since been arrested.
Officials in Gaya last week cancelled the arms licences of Manorama and her husband Bindi Yadav.
The legislator, who was suspended from the ruling Janata Dal-United (JD-U) last week, was evading arrest.
Manorama last Friday filed an anticipatory bail plea despite the fact that police had intensified search operations to arrest her and the district administration had prepared to confiscate her house. Hearing on her plea was deferred by the court on Monday.
Her son Rocky Yadav was arrested on Tuesday from a house in Bodh Gaya for allegedly killing Aditya Sachdeva, the son of a Gaya-based businessman, on May 7. He has been sent to police custody.
Her husband Bindi Yadav, a criminal turned politician, was also arrested in connection with the killing of the teenager.
Aditya's family has demanded a CBI probe into the case and speedy trial to ensure justice.