The family of a murdered scrap metal dealer has faced "no end of threats" and intimidation since his death, one of his sons has said.
David Brickwood, 74, was stabbed and beaten in an attack at his Northampton home in September 2015.
CCTV pictures show vehicles belonging to two of his sons being vandalised outside their homes on Thursday.
Police confirmed an investigation was under way. Nathan Brickwood said he felt "scared and mentally burnt out".
He said people were "trying to intimidate" the family.
"There's been no end of threats but I try not to let it control my life," he said. "I don't want to become scared to walk out the door."
The tyres of Nathan's van were slashed and the windscreen smashed at about 02:20 BST on Thursday.
His brother Dale said his car was rammed and the windows smashed with a hammer at his home nearby only minutes earlier.
He said it was the second time his car had been targeted and it was "taking its toll on the family".
The brothers live at separate addresses in Northampton.
A Northamptonshire Police spokeswoman said: "The offenders caused considerable damage to both vehicles.
"It is believed the offences may be linked and officers are keeping an open mind as to the motive behind the offences. An investigation is under way."
David Brickwood's home in Lindsay Avenue, Abington, was broken into late in the early hours of Saturday 26 September 2015.
He managed to call the emergency services but later died in hospital having sustained 35 stab and blunt-force trauma injuries, an inquest heard.
Officers remain convinced Mr Brickwood died as a result of a "robbery gone wrong" and the intention was not to kill the pensioner.
Seven people have so far been arrested over Mr Brickwood's murder but no-one has been charged, and his sons have previously expressed their frustration at the police investigation.
Speaking last month to mark the third anniversary of the murder, detectives said they believed forensic tests on items found in July could provide a breakthrough.