Why did Lok Sabha pay tribute to Gangster-turned-politician Atiq Ahmed in Parliament?

Mafia-turned-politician Atiq Ahmed and his brother Ashraf were shot dead in front of media persons. They were killed when three assailants opened fire at them near a medical college in Prayagraj. The assailants posed as media persons and were arrested on the crime spot. Now, Lok Sabha speaker Om Birla paid tribute to the gangster in the Lower House.