A man suspected of murder was arrested after three elderly men were violently killed at home a kilometer away.
The discovery of the bodies of twins Dick and Roger Carter, aged 84, and 80-year-old Anthony Payne, was found less than 24 hours apart in Exeter, Devon.
The three deaths were linked because of the "level of violence used," according to police in Devon and Cornwall, who opened an investigation into the triple murder.
A woman living near the Carters said her mother had seen a "wet-skinned man with a tool bag" in front of the home of the elderly twins a few hours before their body was discovered.
The ambulance service alerted the force on Mr. Payne's body on his terrace at Bonhay Road around 3 pm Monday.
And the next day at 1 pm, officers went to the Carter Brothers' home in Cowick Lane after their bodies were found.
A few hours later, a 27-year-old man was arrested for murder and is still in custody at the Heavitree Police Station in Exeter.
The two murder scenes are a little over a kilometer apart, but it is understood that there is no connection between the Carter brothers and the Mr. Payne.
Chief Detective Inspector Roy Linden, of the Major Crime Investigation Team, said, "At present, there are several important common factors between the two addresses.
"Regarding the level of violence used, we decided last night to link the investigations.
"Originally, they were treated as two separate murder investigations.
"A suspect was identified and officially arrested last night."
Mr. Linden did not want to know if any weapons had been used in the attacks or if anything had been taken, but confirmed detectives would not "actively" look for anyone else in relation to the dead.
"There are several important common factors between the two addresses," he said.
"There were a significant number of injuries and commonalities between the two incidents, which led us to link these investigations and treat them as one investigation at the moment.
"Although we believe that a certain course of action has already taken place, on which we are actively investigating, it is still a lot with an open mind."
The police asked anyone in the Bonhay Road and Cowick Lane area between 8 am on February 10 and 1 pm on February 12 to make contact.
Superintendent Matt Lawler, local police commander for Exeter, East and Mid Devon, urged members of the public to check if their neighbors and parents were elderly.
"Based on our current information, we have not yet established a clear link between the parties involved," he said.
"I know that this news will raise important and understandable concerns and is an unprecedented event in our city that has shocked us all.
"While a man suspected of murder has been arrested in connection with these incidents, we must keep an open mind and avoid speculation, as we are still at the very beginning of an already complex investigation." .
"It is vital that anyone with information shares it with us as soon as possible."
At Mr. Payne's home, a handwritten note was left in front of the door: "An 80-year-old man wants housing for himself and his cat. Any response to 65 Bonhay Road. "
It was signed "AG Payne".
Floral tributes were left to the brothers in front of their house, where wooden screens were erected over the doors of the property.
A map said, "For Dick and Roger, we will miss your conversations and your alleys in Sainsbury. RIP, Doris and Fred.
They had previously run a farming business called TrayCrop.
Uniformed officers were also seen removing items from a trash bin near Church Park Road and placing them in evidence bags.
Neighbors said that one of the items looked like a "rocker or sole of a shoe".
Lianne Hill, who lives nearby, said, "They looked well in my garden but could not find anything.
"They never explained what they were looking for and the next minute they went into the driveway and into the adjacent house."
She added, "It's a bit scary when you're so close to home."