An elderly couple in Bristol have been terrorised for more than a year by a man who repeatedly empties bags of excrement in front of their home in the early hours of the morning.

The offender – caught here on CCTV carrying out one of his attacks – has struck 17 times in the last 15 months, always between 4am and 6am, and always at the same property in Staple Hill.

Every incident follows a similar pattern; the offender brings a shopping bag full of animal faeces with him, and pours it either over the front step of the house or on top of the couple's car, parked in their driveway.

He never looks around to see if he's being watched, and always closes the gate behind him when he's done.

Avon and Somerset Police have gone as far as organising an undercover stake out in the hope of catching the man in the act but have had no luck so far and have also been unable to link anyone to the incident through forensic evidence.

Officers investigating the bizarre campaign say they have never seen anything like it, and are hoping the images shown here could help catch him.

Neighbours living near the couple's home say the pair, in their 70s, have been left distressed by the bizarre campaign.

Colin Stone said: "Generally he throws the bag over the wall into my garden, it's part of his little ritual.

"He's quite a distinctive looking person but they haven't a clue who he is and I don't recognise him. He's a bit sick in the head in my opinion.

"He's got this fixation and he keeps doing it. He probably needs help. They're just very nice, normal, lovely people."

Another neighbour, who did not wish to be named, said: "The couple have been there 50 years, since the houses were built.

"He's a crackpot – if I was younger I'd rub his nose in it."

Staple Hill beat manager PC Matt McQuaid says the victims are so intimidated by the attacks that they don't want to be identified.

But they told the officer they were considering moving house to get away from the man, despite having no idea why anybody would do this to them.

PC McQuaid said: "They are completely distraught, particularly the lady.

"They go to bed completely unaware about whether it's going to happen and then they have to clean it up, which isn't pleasant.

"It's gone beyond the point where it's a one- off or a case of mistaken identity, it looks like they're being targeted.

"It's very strange – I've never come across anything like this before.

"Normally people would get bored but this shows no sign of stopping and is quite distressing. We've done everything we can, and he isn't known to the police.

"We have no leads, there's nothing in terms of disputes like a black sheep in the family. We don't have the manpower to have someone sit there until he turns up, so we're hoping people can ID the photo to give us his name."

Anyone with any information should call Crimestoppers on 0800 555 111 or PC McQuaid directly on 07825 280038.