A man whose body was found in a Middlesbrough house died from a stab wound, police said.
The body of the 36-year-old man from Eritrea, Horn of Africa, was discovered at the property in Palm Street on Monday night.
Police said they could not release the name of the victim because they were unable to contact next of kin.
A murder investigation is now under way after a post-mortem examination on Tuesday revealed the cause of death.
Three men, aged 18, 25 and 30, were arrested on Monday and police were granted additional time to hold them.
Officers are appealing for witnesses to come forward, particularly anyone who saw two men arguing outside the Bestbuy convenience store, in Borough Road, or surrounding streets, at about 2000 BST on Monday.