A third person has been arrested in connection with the death of Anita Rose, a mother-of-six who was found unconscious after taking her dog for a walk.

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

Ms Rose, 57, 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.

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.

Detective Superintendent Mike Brown praised the public for engaging with officers regarding the investigation, and issued another appeal for information.

He said: “Whilst we have recovered Anita’s iPhone, her pink zip-up jacket which we believe she was wearing immediately prior to the incident remains outstanding.

“We reiterate our appeal for information as to its whereabouts as it could hold key information or evidence to the investigation.

“The jacket is described as waterproof in material and is believed to be from an outdoor clothing brand, possibly from Regatta.

“We also urge people to please refrain from speculating about the incident, to allow the investigation and any subsequent court proceedings to take place.”

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 Wednesday 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.