Alleged killer John William Cooper made himself a "well engineered" burgling device, it was claimed today (Tuesday).

The tool was found in a field by detectives investigating a violent robbery in Sardis in 1996. Also discovered in a hedgerow was a gun later found to have the blood of murder victim Peter Dixon on one of the barrels.

Forensic scientist Andrew Sweeting told Swansea crown court the device could have been used to prise open doors and windows.

He said he could not think of a lawful use for the tool otherwise it would be possible to purchase one from a shop.

The jury has heard that Cooper was eventually convicted for the Sardis robbery and jailed for 10 years, plus an additional six years for 30 burglaries.

Mr Sweeting said the tool resembled a small car jack. A metal lip placed in a window frame could then be raised, forcing the window open.

It was home made but "well engineered."

Mark Evans, the barrister representing Cooper, suggested the tool could be used in the repairing of cars.

"In a field?" asked the judge, Mr Justice Griffith Williams.

The device and the gun, and several other items, were found on a trail leading from Westwinds in Sardis and in the direction of Cooper's then home.

During the robbery Sheila Clarke was violently attacked in her own home and £6,000 worth of jewellery stolen.

Mr Sweeting said he found a small piece of insulating tape on the tool and similar tape was attached to a torch also found on the "Sardis robbery trail."

A roll of similar tape was also found at Cooper's then home in St Mary's Park, Jordanston.

Mr Sweeting said he accepted that the tape was very common and could be bought in any DIY shop or supermarket.

Mr Sweeting told the jury he examined the double barrelled shotgun and found that the barrels had been painted with black gloss paint. He also found black gloss paint on a trainer recovered from Cooper's house.

He also examined tins of paint from the house but none of them matched the gloss on the gun or the trainer.

Mr Sweeting also inspected a length of cord tied to the gun and a length at Cooper's house. Both was constructed of nylon 66.

And inside the torch there was a small piece of colourless, cotton cloth. A piece of the same general appearance, weave and thickness, was found inside a cartridge box dug up from the garden of Cooper's home.

Mr Sweeting said there was nothing unusual about the paint, cord or the cloth, all of which had been in common usage.

Cooper, aged 66, now of Spring Gardens, Letterston, denies murdering Peter and Gwenda Dixon, aged 51 and 52, in 1989. They were intercepted as they walked the Pembrokeshire Coastal Path, tied up and shot dead.

Cooper also denies the murders of brother and sister Richard and Helen Thomas, 58 and 56, who were shot dead at their home, Scoveston Park, four years earlier. The building was then set on fire.

Cooper has also pleaded not guilty to a rape, indecent assault and five attempted robberies.

The trial continues.