Forensic archaeologist Lucy Sibun (36) explained that she assisted the police in identifying the location of and recovering buried remains.

She agreed she was involved with a colleague in an excavation at the rear garden at the house at 50 Irvine Drive in Margate.

She explained that they would look at differences in soils to find areas that may have been disrupted.

In this case, ground-penetrating radar had picked up an anomaly that highlighted a particular spot in front of a small shed.

Once digging commenced, they came to a layer of sandy cement. Further work was done to break into that concrete, she said.

Ms Sibun said the digging was not something that had been done in a hurry.

She told the court that, “neat regular edges,” and the absence of spade marks in the sides suggested someone had taken their time to carry out the job.

She said she and her colleague, with help from police, carried out the excavation at the site of the radar anomaly below the surface.

Once the sand and cement layer was prised up, more soil covered two black plastic bags.

The first was removed, placed on a black plastic sheet and examination revealed more than one layer of plastic bag below.

Removal of the layers continued until the discovery of hair.

When both bags were removed from the site, digging continued through a loose chalk and soil mix until reaching a solid chalk base.

In conclusion, she said the neat, regular shape and size of the grave suggested it was not excavated in a hurry.

Clear differences in the types of soil within the grave suggested there had been, whether by accident or design, two separate piles of soil removed during the excavation.

The lowest layer contained more chalk and less topsoil, whereas upper layers contained more soil and less chalk.

A step had been cut inside the grave and this may have been to make it easier to get in and out.

It may also have been because digging became harder once the chalk was reached and the decision was taken to reduce the size of the hole being dug.

She noted in her report that one corner of the capping layer of cement had been disturbed by the subsequent burial of a dog and tortoise and this had also disturbed the soil layers.

Cross-examined by defence counsel Donald Findlay QC, the witness said the hole would have been about three feet by two feet to a depth of just under three feet.

The layer of sand and cement was about five centimetres thick and cracked as it was prized up.

Mr Findlay put it to her that what she was saying was that a hole had been dug, soil replaced, concrete added and soil placed on top of it.

She said that was the case and in answer to Mr Findlay, estimated the digging of the hole would have taken one to two hours, although it was difficult to say because there were so many variables.

Mr Findlay suggested that as the layer of sand and cement bore no marks of soil settling into it, it must have been allowed to set before the final layer of soil was put on top of it.

Because of the nature of the mixtures of soil, she said, it was her opinion what had taken place was carried out as a single exercise, but added that it need not be necessarily so.

She agreed that in a modern graveyard, for example, it was possible for layering to take place but she did not think that in relation to the site in Margate that this was what had happened.

Again she said this was because of the mixture of soils they found.

Mr Findlay put it to her, that with her expertise, it was not possible for her to say when the hole was dug.

She agreed she could not say when the original excavation took place.

Earlier today, the resident of 52 Irvine Drive, David Martin (57), identified Tobin as a former neighbour.

Shown tenancy records for number 50, he agreed they gave the start date of Tobin’s tenancy as March 25, 1991, and the end date as December 15 that year. A woman was named as his co-tenant but he did not recall ever meeting her.

Doctor Mary Hodgson (58), a GP based in Paisley, said she had handed a set of medical records for a Peter Tobin to Lothian and Borders Police.

She agreed that the file she provided included records for Mr Tobin from a practice in Bathgate.

Zoe Miller (29), a scenes of crime officer with Essex Police said she was present during the excavation in Irvine Drive. Two black polythene bags were removed from a grave, she continued.

They were found to contain the upper and lower parts of a body and were given identification numbers ZM8 and ZM9 and placed in sealed body bags.

Mr Mulholland then told the court he intended to play a computer presentation to show as sensitively as possible how the body was placed in the plastic bags. The court was shown the presentation, which revealed that the lower half of the body was found with the legs bent at the knees.

On the upper half, the arms appeared to be bent at the elbow, towards the face.

Miss Miller said that the following day, on November 13 last year, she attended the post mortem on the body which was carried out at the Queen Elizabeth the Queen Mother Hospital, in Margate.

The trial continues.

— The charges —

Tobin denies that on February 10, 1991, in Bathgate, he abducted or induced Vicky Hamilton and at his home in Bathgate, or elsewhere in Scotland, assaulted, drugged and struggled with her, compressed her neck, indecently assaulted her and murdered her.

He also denies that between February 10, 1991 and December 15 the same year, at his home, at St Andrew Square in Edinburgh, at an address in Margate and elsewhere in the UK he attempted to defeat the ends of justice by concealing Vicky’s body, depositing a purse belonging to her with intent to mislead police, bisected her body then buried her body parts.

Tobin has lodged a special defence of alibi.