A drug addict found dead in a Teesside flat was probably murdered for a drugs debt, police revealed yesterday.

Robert Parkin, 29, was savagely beaten several times over the course of four or five days before he died from his injuries in a top floor flat in Shaftesbury Street.

Police have now arrested a man and two women suspected of being involved in his violent death and confidently predict their man hunt will lead to more arrests.

Mr Parkin, a likeable drifter known locally as Swampy, sometimes sold the Big Issue homeless magazine in Stockton town centre.

He was discovered lying on a makeshift bed in the flat's kitchen.

The heroin addict, who was known to the police, had been beaten black and blue but had refused hospital treatment in the weekend before his body was discovered last Thursday.

Detective Superintendent Mark Braithwaite, who is leading the operation, said yesterday: "We are now treating this as a murder inquiry, and as a result, we carried out a large scale operation in the early hours of this morning at a number of Stockton addresses.

"We arrested three people on suspicion of being involved in Robert Parkin's murder and they are now being held for interviews at police stations across Cleveland."

He added: "It is my belief that the cause of this attack was a drugs debt and that violence continued against him for the next few days." The results of forensic tests carried out on the body, flat and items recovered from the flat, are not expected to be known for several weeks.

Police now want to speak to anyone in the Shaftesbury Street area, which includes large ethnic minority and asylum seeker communities, who knew Mr Parkin or his associates.

Det Supt Braithwaite added: "It is evident that he was well-liked and there is considerable sympathy on the street for him. But we want that sympathy to be turned into action and want people to contact us."

Anyone with information can contact Det Supt Braithwaite on a confidential hotline, on 07771 771314, the incident room at Cleveland Police headquarters on 01642 302389 or Crimestoppers on 0800 555111.