A man who was beaten up by a group of men last week on suspicion of being a mobile phone thief, died from his injuries in a city hospital on Tuesday.

Police had arrested four men for the assault. They will now be charged with murder, officers said.

Mohammad Sikandar, 36, a resident of Tiljala Masjid Bari Lane, was allegedly kidnapped twice and beaten up by the group, who suspected him of stealing a mobile phone while they were engaged in a shifting job on Kustia Road in Karaya, not far from Park Circus.

This was the second case of lynching in the city in less than a week.

“According to the statement of the deceased’s sister, Sikandar was picked up twice — once on Monday and then on Tuesday — and left in their neighbourhood after being badly beaten. However, when the men picked him up again on Wednesday, Sikandar did not return. His family launched a search and found him hidden in a room off Kustia Road in a critical condition,” said an officer of Karaya police station.

Sikandar was found with his hands and legs tied, the police said.

Officers said he had suffered grievous injuries, including a fracture in his right leg, swelling on the forearm and a bump on the forehead. He was taken to Calcutta National Medical College and Hospital.

“His condition deteriorated, and he was shifted to a private hospital. A case was registered at Karaya police station based on his family’s complaint, and later, four men were arrested,” said the officer.

The police identified the accused as Zahid Hossain, Bikas Routh, Sahil Ali, and Manwar Hossain alias Rocky.

Sikandar died on Tuesday morning, prompting the police to escalate the charges and add the section of murder.

“The way the victim was repeatedly beaten leaves no doubt that the attackers were fully aware of the consequences. Their motive was also clear — they suspected him of stealing a mobile phone, which remains unproven,” said a senior police officer.

Deputy commissioner (south east division), Kolkata Police, Bholanath Pandey, said the investigating officer would move court on Wednesday to add the murder section.

This was the second alleged lynching in the city. A gold trader died on Sunday after being beaten in Behala’s Parnasree for allegedly using fake gold to secure loans worth several lakhs.

The trader from Rajasthan and his son-in-law were assaulted by a group of jewellers and a developer for allegedly cheating several by taking money against mortgaged jewellery.