Criminals frequently change address to escape authorities. Sometimes they even cross over to neighbouring countries.
Take the case of Babloo Dubey, 30, one of Bihar's most wanted criminals-involved in dozens of murders and abductions---who was arrested last month in Kathmandu by a team of Nepal police.
While Bihar police was trying to nab the gangster, he was safely residing in a flat in Nepal's capital. During his eight-month stay in the Himalayan nation he even operated an eatery in another Nepal town.
On Tuesday night, a week after his arrest, he was released on bail and secretly handed over to Indian authorities. Police here say there's no evidence of Babloo committing any crime in Nepal.
There's no official announcement of the handover since both countries don't have an extradition treaty and criminals and terrorists are routinely transferred in this manner and shown as arrested on the other side.
Babloo's arrest is one of the many instances of criminals from Bihar using Nepal as a safe haven to escape the police dragnet and carry on with their activities unhindered.
Over 700 km of India's 1,751-km long open border with Nepal falls in Bihar and authorities here believe crackdown on criminals by the Nitish Kumar government is responsible for their influx.
"There have been instances in past of criminals from Bihar operating in Nepal, but their activities have increased following Kumar's clean-up campaign," said a senior police official on condition of anonymity.
A day after Babloo's arrest, Kathmandu police nabbed seven robbers from Bihar's Motihari district involved in nine instances of robbery in the capital.
Last November, Nepal police had arrested Zakir Hussain, a Bihar MLA for his alleged involvement in abduction of a Nepali businessman 10 years ago.
There's also a rise in cases of criminals from Bihar abducting Nepalis for ransom.
Some use hideouts in Nepal to shelter hostages kidnapped in the Indian state. In July last year, Santosh Gupta, owner of an FM radio channel in Nepal's border town of Birgunj was murdered by criminals in Bihar.
The problem is more acute in the districts bordering Bihar, but criminals also make way to Kathmandu and other important cities to carry on their activities.
The issue of growing cross-border crime was raised during the home secretary level talks between both countries in Kathmandu on June 1 and both sides agreed to share intelligence to curb the trend.