Detectives have been granted more time to question a suspect in the murder of a 57-year-old dog walker in Suffolk.

The man, who is in his 20s, was arrested on suspicion of murder on Wednesday – a week after Anita Rose was found injured and unconscious near Rectory Lane in Brantham, Suffolk Police said.

Ms Rose, a mother-of-six, left her house to take her springer spaniel named Bruce for a walk at around 5am on July 24, according to the force.

She was found by a member of the public at around 6.25am and taken to Addenbrooke’s Hospital in Cambridge with serious head injuries, where she died on Sunday.

The man, who is from Brantham, was taken to the Martlesham Police Investigation Centre for questioning and remains in custody.

Detectives have been now granted a further 12 hours to detain him after officers applied for a warrant on Thursday.

He is the third person to be arrested in connection with Ms Rose’s death after two people from Ipswich were arrested on Saturday, including a 45-year-old man held on suspicion of attempted murder and later re-arrested on suspicion of murder.

A 37-year-old woman was arrested on suspicion of handling stolen goods, and both have since been released on police bail, with conditions to return on October 25.

A Home Office post-mortem examination failed to establish the cause of Ms Rose’s death on Tuesday, after which Suffolk Police said it was continuing to investigate the case as a murder.

Police have urged local residents with CCTV or doorbell cameras to review their footage and passengers travelling on trains towards Ipswich, Colchester or Manningtree on the morning of July 24 who may have seen anything suspicious to contact the force.

Anyone with information is urged to contact the investigation team at Suffolk Police quoting 37/41580/24 or by phoning 101.