OFFICERS from the Major Crime Investigation Team (MCIT) searching a pond in Ramsbury and have discovered some women's clothing nearby.
Today, specialist search teams have been draining the pond so that fingertip searches can take place of the silt at the bottom.
Officers have also discovered a pile of material, thought to be women's clothing, 100 yards away from the pond.
Buried under a few inches of mud, detectives have removed the material, amounting up to 60 pieces, some of which are believed to be clothes.
The items will be sent for forensic testing but officers are keeping an open mind as to why they are there and that they may not be linked to the investigation.
In addition they have found a 'chunky knit cardigan' which was discovered near to the pond.
Wiltshire Police are satisfied that these clothes did not belong to Sian O'Callaghan.
Detectives are keeping an open mind around all of the findings and as to why the shotgun or clothing might be at the location.
Lead investigator, Detective Chief Inspector, Sean Memory said: “The clothes were buried a few inches beneath the surface, and one was marginally exposed which is why we were able to find it. We do not yet know the significance of this, but someone has clearly made some effort to hide it.
"We are keeping an open mind about it. There may have been fly-tipping involved, and there could be a perfectly innocent explanation.
"We can be sure that none of the clothes belonged to Sian. Forensic investigations will now carry on into next week to identify the owners of the clothes."
A 'left' boot was found at the site on Thursday, May 15.
On Friday, May 16 team's also found the 'right' boot believed to be Sian's.
In addition, on Friday officers found a single barrelled shotgun.
The boots and the shotgun were found in the pond at the site. The material/clothing was found a short distance away from the pond, while the chunky knit cardigan was found near to the pond.
Sian O’Callaghan aged 22 from Swindon was abducted and murdered in March 2011.
Searches will continue over the next few days.