Police were called to the home of Moors Murderer Ian Brady's confidante Jackie Powell after a car outside was vandalised.
Residents at the Brynhyfryd estate, South Wales, were shocked when they awoke on Saturday morning to find white paint splattered across the vehicle, which was parked outside Ms Powell's house.
The rear of the silver soft-top Renault had been covered in white paint, with a trail of it leading up to the car.
Neighbours said they believed the vehicle belonged to Ms Powell who, they said, had only returned to the house on Friday.
Police, however, were unable to confirm who the owner is.
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Now they fear they could get caught up in potential vigilante attacks because of Ms Powell's links to serial killer Brady.
One neighbour said it had happened during the night.
"I didn't see anything, but I woke up and the car was covered in paint," she said.
"It could have been anyone."
"We are a bit too close to it."
Ms Powell's next-door neighbour Julia Howells said: "I think it's been a long time coming to be honest.
"Obviously with my car being in the drive maybe it could be a target.
"I really think the message is strong now, just go away please and don't come back."
And another neighbour Wendy Williams said: "This was my concern originally, because it was so publicised, that something would happen.
A police spokeswoman said police were investigating.
She said: "Dyfed-Powys Police are not able to confirm who the victim of crime is but we can confirm that a vehicle was damaged in the Brynhyfryd, Llangennech area.
Inquiries to trace those responsible are now under way."