Patna, Jan. 29: They led an affluent, respectable life in a plush house and moved around in luxury cars till the police arrested all men in this family in Banka district for robbery.

Bateshwar Mandal, in his early 50s, and his three sons were arrested on Wednesday for a bank robbery. The four allegedly escaped with Rs 11.63 lakh in cash after shooting at and critically injuring a security guard and an employee of State Bank of India's (SBI's) Dudhari Bazaar branch in Banka on January 23. On Thursday, Rahul Kumar of Nath Nagar was arrested for alleged links with the gang.

Banka superintendent of police (SP) Satya Prakash said a special investigation team (SIT) probing the bank robbery zeroed in on Bateshwar Mandal of Vijay Nagar. Subsequently, Bateshwar was picked up from his house for interrogation.

Initially, SIT members were reluctant to search Bateshwar's house as he seemed to be a prosperous farmer. But they raised eyebrows at the fleet of luxury cars in his sprawling compound. A search yielded Rs 5 lakh in cash, eight country-made pistols, 50 live cartridges, 9 bombs and a huge amount of explosives. They were stunned when Bateshwar admitted his three sons - Nagmani alias Manish Mandal, Pandav Mandal and Angad Mandal - were behind the January 23 Dudhari Bazaar SBI robbery.

Banka SP Satya Prakash said it was the first time he came across a family where every male member was involved in crime. 'The gang, comprising the family members, had also planned to rob banks at Kakbara and Makdumma in Banka district,' Prakash told The Telegraph over phone from Banka.

He claimed the seized cash was part of the money looted from SBI. 'A motorcycle used in the robbery was recovered from Bateshwar's house. We have enough evidence to show the family's involvement,' he said.

The SP said the gang was active for almost a decade but had never been arrested. 'We plan to submit a proposal to state police headquarters to initiate the process of confiscating their property,' he said.

Bateshwar, however, said he had received Rs 50 lakh as compensation from the government after it acquired his land. The police have seized his ATM cards and some bank passbooks to verify his statement.

'The bank accounts have been frozen for investigation,' the SP said.

An investigating officer said Bateshwar's daughter-in-law (whose identity is being withheld as her name does not figure in the FIR) told senior police officials that he (Bateshwar) used to harass his sons whenever they protested against his diktats. 'He had forced his sons to step in the netherworld of crime,' the police officer quoted the daughter in-law as saying.

Earlier, the government railway police arrested a Rohtas-based medical practitioner, his son and a grandson on the charge of committing robberies on running trains on the Gaya-Mughalsarai section of East Central Railway. The family had also earned huge wealth through unlawful means.