A 26-year-old undertrial prisoner in Arthur Road jail allegedly committed suicide in the early hours on Monday.
Jail officials said that he was mentally ill and was undergoing psychiatric treatment at the prison hospital for the past three and a half months.
Officials said that the deceased, Sabir Ali Shaikh, was an undertrial for the past three years at the Arthur Road jail in central Mumbai.
They informed that Shaikh died after he used a bedsheet to hang himself in a room in the prison hospital at around 4 am on Monday.
Officials added that no suicide note was found at the spot and further investigations into the incident were underway.
Officials said that he had attempted suicide in January as well but was saved by alert prison guards.
Shaikh had three murder cases registered against him, including one at MIDC police station in suburban Andheri, officials said.