Union minister Kaushal Kishore's son has been booked under the Arms Act, a day after a 30-year-old man was shot dead under mysterious circumstances at his home in Lucknow, the police said on Saturday.
Three men were arrested in connection with the case on Friday, the police said.
According to the minister, his son Vikas Kishore lives at his Lucknow residence but he was in Delhi when Vinay Srivastava, described as his friend, was murdered at the house.
The pistol used by the accused to shoot Vinay is a licensed weapon owned by Vikas.
His arms licence was valid only in Uttar Pradesh, so he did not take the pistol with him, Kaushal claimed.
"On September 1, Vinay was killed at Vikas's residence in which his licensed pistol was used. In this connection, a case has been registered against the licensee at Thakurganj police station under section 30 (punishment for contravention of licence or rule) of the Arms Act," Deputy Commissioner of Police (Lucknow West) Rahul Raj said.
The victim had a single gunshot wound to his head, Raj said.
The report for cancellation of the licence has been forwarded to officials, he said.
On Friday, three men -- Ajay Rawat, Ankit Verma, and Shamim alias Baba -- were arrested in connection with the murder that took place at the Union minister's house in the early hours of the day, police said.
According to a complaint filed by the victim's brother, the three men had invited Vinay for dinner at the minister's residence, where an altercation took place in the course of gambling.
In the initial investigation, it was revealed that before the incident took place, Vinay, Ajay, Ankit, Shamim and two others -- Saurabh Rawat and Arun Pratap Singh alias Bunty -- were playing cards for money and also had alcohol, police said.
After some time, at the instruction of Ajay, Ankit and Shamim, Saurabh and Arun took their win and left, they said, adding that Vinay had lost Rs 12,000 in gambling.
Vinay got angry at this and confronted the three with accusations of ganging up against him, they said.
"Because of you, I have lost money, if the game was on, I would have won back the amount, Vinay had said," the police said in a statement.
This led to a fight among them, blows were exchanged, and Vinay lost a button of his shirt in the fight, which enraged him, the police said.
As the fight went on, Ankit took out the licensed revolver of the minister's son which was kept under a pillow.
The three caught hold of Vinay, and Ankit shot him in the head, killing him immediately, joint commissioner of police (crime) Akash Kulhary said, adding the incident happened around 4 am.
The CCTV footage showed Saurabh and Arun leaving the house before Vinay was shot, the police said.
The police recovered a .32 bore revolver, ammunition, a pack of cards and Rs 2,000 cash from the spot on Friday.
SHO of Thakurganj police station Vikash Rai told PTI that "the pistol (used in crime) was manufactured in Kolkata".
The land on which the house is built belongs to Kaushal Kishore, the Union minister of state for housing and urban affairs and BJP MP from Lucknow's Mohanlalganj (SC) constituency. But the house is yet to be registered, said Jai Devi, the minister's wife.
Jai Devi is a BJP MLA from Malihabad (SC) assembly constituency.
Kaushal is a second-term Lok Sabha MP from Mohanlalganj (SC) parliamentary constituency and was an MLA from 2002 to 2007. He was also a minister in the UP government from 2003 to 2004.
