A 23-year-old undertrial prisoner committed suicide on the premises of the Parappana Agrahara Central prison on Sunday evening.
The police have identified the deceased as Vinod, a resident of Adugodi, who was lodged in prison for allegedly preparing to carry out a dacoity.
Police said he was arrested by Adugodi police on May 21 and later produced in court. He was then remanded in judicial custody.
The Parapana Agrahara police said Vinod committed suicide by hanging around 6.45 pm behind the prison kitchen. His fellow inmates found him and took him to the hospital for treatment.
Later, he was shifted to Victoria Hospital for treatment where he died.
Police have registered a case of unnatural death and a further probe is underway.
Meanwhile, as per procedure, a magisterial enquiry will be conducted into the incident. Police said the incident had revealed loopholes in prison security.