A man was being questioned on Monday over the murders of a clergyman killed at his vicarage and a pensioner stabbed to death at her home.
Stephen Farrow, 47, was arrested in Folkestone, Kent, on Sunday on suspicion of murdering the Rev John Suddards, 59, in Thornbury, South Gloucestershire, last Tuesday.
Police also arrested him over the death of retired teacher Betty Yates, 77, who was killed at her cottage in Bewdley, Worcestershire, on January 2.
Farrow was detained by Kent Police at around 4.20am after Avon and Somerset Police launched a nationwide appeal and officers received a tip-off from the public.
West Mercia Police officers investigating Yates's death said yesterday the two murders had been "formally linked".
A spokesman for the force said: "It can also be confirmed that, following close liaison with Avon and Somerset Police, detectives have formally linked the murder of Mrs Yates to the murder of the Rev John Suddards in South Gloucestershire.
"Reverend Suddards, 59, was found dead in his home in Thornbury on Tuesday February 14, 2012. Like Mrs Yates, he had been stabbed to death."
The spokesman confirmed a 47-year-old man was arrested in Kent on behalf of the force and was being transferred into the custody of Avon and Somerset Police.
Detective Chief Inspector Neil Jamieson said: "We would like to thank Avon and Somerset Police for their help in our investigation. We have been working with them to examine similarities between the deaths of Betty Yates and the Rev John Suddards."
Suddards was found stabbed to death at his home in Castle Street in Thornbury by workmen who arrived at the vicarage next to St Mary's Church and found it was locked. When they were let into the house they found his body.
The news of his death sent shockwaves through the clergy and the close-knit community, which lies about 11 miles north of Bristol.
A candlelit vigil to mark a week since he died will be held tonight at St Mary's Church, according to the church's website.
It said it was being held between 10pm and midnight, saying it was "the time of his death last week".
After taking the Sunday morning service at St Mary's Church yesterday, the Venerable Geoffrey Sidaway, Archdeacon of Gloucester, said clergy should continue to open their doors to "people who are distressed and angry" in the wake of Suddards' murder.
He said: "By the nature of the position, clergy are often dealing with people who are distressed and angry, and that can put us in very vulnerable situations."
The St Mary's vicar took up his post only last July, having come from the diocese of Chelmsford in Essex.
Former barrister, Suddards moved to the area after serving at St Nicolas Church in Witham, Essex, since 2001 and before that at Great Yeldham parish, 20 miles away in Essex.
Police seized a white Citroen van at about 11.30pm on Tuesday, just hours after arresting a 43-year-old man over Mr Suddards' death. He was later released on bail.
It is believed a man in his 40s had been sleeping in the van.
Yates was found dead at the bottom of stairs at her home on the banks of the River Severn on January 4, having been killed two days earlier.
West Mercia officers investigating Yates's killing arrested and questioned a man on February 2 before he was released on bail.
Police later issued descriptions of two men, one in his late 20s or early 30s and one in his mid-to-late 40s, seen close to her home on the day they believe she died. They were seen by walkers during the mid-afternoon of January 2 in the area between the Riverside Caravan Park and Riverscroft Cottage, where the pensioner was stabbed.
After her death Yates's son and daughter made an emotional appeal for help to bring their mother's killer to justice.
Hazel Costello, along with brother David Yates, said: "We are completely bewildered as to who could carry out such a savage attack on our mother. That this should have happened in her home makes this even more difficult to bear."