Guwahati, Oct. 5: Police here today said Bubu Konwar, the "most wanted" car thief, arrested last night, was also the "kingpin" of a five-member gang of contract killers, extortionists and gunrunners.

Konwar, 34, alias Binod Gogoi and Binod Konwar, also a former Ulfa cadre, landed in the police net here while selling country-made pistols in the city's Latasil area.

"He was on his way to deliver a pistol to a person from Nalbari in the Malibagan area of Kharguli under Latasil police station. We found a 7.65mm pistol, one magazine and seven rounds of bullets from him," a police officer investing the case said today.

He said Bubu was the prime accused in the murder of a driver from the Noonmati area of the city, Dhiraj Talukdar, on August 29.

Bubu had shot the driver on his head from point blank range before taking away his car along with five other members of his group at Amguri in Upper Assam's Sivasagar district.

The other five accused - Phugholi and Priyanka Gogoi (both Bubu's wives), Amiya Das, Papari Dutta (wife of Amiya) and Ananta Konwar - were earlier arrested and are in judicial custody. "Phugholi had rented the cab from Hatigaon and along with Amiya and Priyanka, went to Amguri where Bubu and Ananta were waiting. He then killed Dhiraj by shooting two rounds on his head and dumped the body in Jaji river," said the police officer.

Bubu, a resident of Ratanpuria Gaon under Amguri police station in Sivasagar district, was involved in several other criminal cases in Upper Assam. Sources said he was an Ulfa cadre and used to operate from Dimapur in Nagaland.

"An Ulfa cadre in 2009 had confessed that Bubu used to supply and safeguard arms and ammunition for the outfit from Dimapur. He used to carry those to Guwahati by train," the source said.

He served a term in Sivasagar jail along with seven others for the murder of a Jorhat-based businessman Kailash Agarwala Ginoria in 2012.

The trader's body was dumped near a stream. Bubu was in the headlines again last year when he was arrested for extorting a flour-mill owner in Jorhat in the name of Ulfa (Independent).

Amanjeet Kaur, superintendent of police, Jorhat, told The Telegraph that Bubu was out on bail when he later murdered a headmaster of a school in Jorhat. "Bubu came out on bail and was hired by Saurav Gogoi, son of Dijendra Nath Gogoi, to murder his own father. Bubu shot him on the school premises," Kaur said.

Bubu's father, Lahon Konwar, was also involved in the murder of the headmaster.

Bubu was produced in the court of Kamrup (metro) chief judicial magistrate today and was remanded in six days' police custody.