A 27-year-old man, out to celebrate his MBBS graduation, allegedly beat a man to death with the help of his brothers and three friends on Thursday morning after a spat over refusal of an ice-cream treat. The incident took place in outer Delhi’s Rohini, police said.

The four suspects escaped from the spot after the murder, but the police identified and arrested them within hours after seeking help from eyewitnesses and examining CCTV footage to ascertain the registration numbers of their motorcycles.

The police identified the victim as Amit Sharma, a Rohini resident who ran a motor oil manufacturing unit with his father. The incident started late on Wednesday night, when Sharma was having ice-cream out on the streets of Rohini Sector-6, with his brother-in-law and a friend.

In the same neighbourhood, two brothers — Lakshay and Karan — and their friends, Dhiraj and Avinash, were out celebrating Lakshay’s success in his final year MBBS exams. He had completed his MBBS from a college in Meerut, said the DCP. “After their celebrations, the four visited the ice-cream stall where Sharma and the other men were already present,” said SD Mishra, deputy commissioner of police (Rohini).

“When the four suspects ordered ice-creams for themselves, they also offered to pay for the ice-creams of Sharma and two other men as part of their celebrations. But Sharma turned down the offer. That led to an argument,” said the DCP.

The altercation was quelled at that time. But the suspects decided to confront Sharma, his brother-in-law and friend soon after.

“The four men intercepted the trio for a second time near a school around 12.30am and attacked them with a stick. Sharma suffered head injuries to which he later succumbed,” said the DCP.

When the police began their probe, they came across an eyewitness who had noted down parts of the registration number of the suspects’ motorcycles. CCTV footage helped investigators ascertain the vehicle registration numbers after which all four were arrested, said the DCP.

The officer said that Lakshay’s brother, 29-year-old Karan, works as a sales executive with a motor firm. The third suspect, Dhiraj too works as a sales executive with another motor firm. The fourth man, Avinash, runs an auto spare parts shop in Mayapuri.