That was before they received a telephone call - they have never said from whom - saying that Heather West, 16, had been missing since 1987, and suggesting they investigate. On 16 February, their inquiries took them to 25 Cromwell Street, Gloucester, Heather's last-known address, which has been dubbed by the media the 'House of Death'.
Cromwell Street is narrow, has largely terraced houses close to the city centre, and with a park near by. The Wests' three-storey house is in dilapidated condition with peeling green-painted window frames and cracked stucco. Next door is a Seventh-Day Adventist church where a poster asks: 'Is there hope for the world?'.
According to neighbours the condition of number 25 mirrors the decline of the area from a safe, quiet residential family area to one where many of the homes have now been divided into flats, with a fast-changing and largely anonymous population.
The police dig began in rain so heavy that officers had to call in the fire service and council engineers to pump out waterlogged excavations and advise on safety. At this stage neighbours thought the plain-clothes investigators were workmen looking at a problem with the drains.
In fact, beneath a patio they had uncovered the decomposing remains of a teenage girl, which were taken first to Gloucester police station, then to the university in Cardiff for scientific examination. Police made an appeal for information on the missing 16-year-old, hoping that perhaps she had changed her identity and made a life elsewhere in Britain. There was no response.
The end-of-terrace house is owned by Frederick West, 52, a builder, and on 25 February he and his wife, Rosemary, 40, were taken in for questioning. Three days later, on 28 February, Mr West was charged with his daughter's murder, and remanded in custody. His wife was released on police bail.
The following day two more bodies were found by police digging in the 60ft by 15ft garden; both had been in the ground for many years. By now police were scouring missing persons records back to the 1970s, and searching with powerful machinery.
Last Wednesday an elderly couple, former occupants of the Wests' house, were brought in by police to point out alterations made since they left 25 years ago. Flowers began to arrive on the doorsteps, and the crowd of reporters, photographers and television crews were joined by a growing throng of curious onlookers.
Last Thursday, Mr West was charged with a further two murders - of a pregnant lodger in his home, Shirley Anne Robinson, 18, and another unknown woman. As the charges were read out in Gloucester magistrates' court, he slumped against the sides of the dock, arms outstretched above his head, a short man with curly hair and sideburns, dressed in a blue cardigan, open-necked shirt over a T-shirt, and grey trousers. Reporting restrictions were not lifted.
The police had started to use a 'magic eye' body detector, capable of detecting human remains in concrete. The surface-penetrating radar, which looks like a flattened lawnmower, was developed to find mines after the Falklands war. It can detect a hollow up to a mile below ground.
Last Friday, pneumatic drills arrived to demolish an extension at the back of the house, and to smash through the floor of a concrete playroom in the basement.
The remains of a fourth body were found and, like the others, examined on site by a Home Office pathologist, Professor Bernard Knight, 62, (whose accomplishments include 10 published crime novels) and then taken to Cardiff for further tests.
By now, 70 officers were on the case, and the police check of missing persons files had uncovered unsolved cases in the area, including Mary Bastholm, 15, who was last seen leaving home to visit her boyfriend, and a student, Lucy Partington, 21.
Mary was a waitress. She was last seen in 1968, waiting for a bus on her way to nearby Hardwicke to play Monopoly with her boyfriend. Scattered pieces of the board game were found at the bus stop, but despite a huge search Mary was never seen again.
Miss Partington, a student at Exeter University, was last seen on Boxing Day 1973 when she left a friend's home in Cheltenham to catch a bus to her mother's home at Gretton near Winchcombe.
Over the weekend, the real-life drama had become a full-blown public spectacle. Last Saturday a fifth body was found, in a cellar at the rear of the house, on Sunday a sixth, and on Monday a seventh, all three in the basement.
Yesterday, the eighth set of remains was found in the ground-floor bathroom, and police began to speculate that a final toll of 14 was not impossible, putting the case aong the worst British serial killings. Peter Sutcliffe, the Yorkshire Ripper, killed 13 women between 1975 and 1980; Dennis Nilsen strangled 15 men from 1978 to 1983, while John Christie, of 10 Rillington Place, Notting Hill, west London, killed eight London women between 1949 and 1953.
The police prepared to widen the search, and a guard was placed on a large semi-detached house almost a mile away, at 25 Midland Road, Gloucester - where Mr West lived for more than 20 years ago before moving to Cromwell Street. Police are also planning to look at a caravan park in Bishop's Cleeve, near Cheltenham, where he worked. A field has been sealed off and marked out with a stake.
The police missing persons bureau yesterday issued a photograph of Mr West's first wife Catherine, who has not been seen by relatives for 20 years. The image has been enhanced by computer to simulate how she would look now.
None of the deceased has been formally identified and their ages and causes of deaths not yet established. At Cromwell Street the search will go on today. Mr West is due in court again on Friday.