Cuttack, Feb. 4: Police are struggling to extract information from the gangster siblings - Sushant and Sushil Dhal Samant - about Dipu Mallick, whom they have allegedly killed.

The gangster brothers are proving to be tough nuts to crack for the team of experienced investigators with the two dodging questions on the case. Though the cops' focus is on recovering the body and solving the murder mystery, they are yet to come up with anything positive.

Sources said both the Dhal Samant brothers had denied their involvement in the Dipu Mallick murder case. They have not co-operated in the interrogation process even though three days have passed after they got arrested.

"However, we have got other vital information regarding their crime syndicate and their several associates," a police official said.

Already, the statements of the victim's father, Adwita Mallick, and some other key witnesses have been recorded.

The police said there was credible circumstantial evidence against the gangster brothers and efforts were on to collect more physical evidence to ensure a logical end to the case.

The victim's father, in his petition, alleged that the gangster brothers had killed Dipu after abducting him in November 2013.

The brothers were arrested from Bhubaneswar on January 28.