Jamil, along with four others, including a woman, had been sentenced to life imprisonment by a court four days ago in a murder case, died this morning, police said.
He was serving jail in the murder case of one Bhola which took place in 2007 and was lodged in barrack number 7A.
"Prisoners told me that Jamil suddenly started hitting his head on the cell's wall around 8 AM and fell unconscious. He was rushed to district hospital where he was declared dead.
However, Jamil's family has claimed foul play in his death. The deceased's brother Mohammed Sarif alleged that he had been murdered.
Police said they are questioning other prisoners to get leads in the case.