The victim, Brijesh Kumar, had invited his friend Bhola at his house for a party in northwest Delhi's Sukhdev Nagar on October 9, they added.
Kumar and Bhola had an argument after the former did not allow the latter to smoke in his house. When Bhola did not agree, Kumar slapped him, the police said. Bhola felt insulted and decided to take revenge.
Bhola contacted his other two friends -- Vijay and Arjun -- and asked their help in killing Kumar, police said.
The trio invited Kumar for a party on October 10 and made him drink too much. Later, they took him for a drive and then shot him in the head, the police said.
Meanwhile the police recovered a body of a man in a canal near Rohini Sector 16, which was later identified as that of Kumar.
Kumar's family told the police that he did not have any enemies. However, they told them about the fight that took place between Kumar and Bhola over the issue of the latter smoking a cigarette, the police said.
His friends were found to be on the run. They were caught yesterday, they added.
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