Within hours of the disappearance of Holly Wells and Jessica Chapman, the caretaker charged with their murders was asking police whether he was a suspect, the Old Bailey was told yesterday. Two days later, Ian Huntley tearfully told a detective, "You think I have done it". The officer told him not to persecute himself.

As the third week of the trial opened, the jury of seven women and five men heard how the 29-year-old caretaker had three scratches along his jaw on 5 August last year, the day after the girls vanished. He had spoken to police and townspeople in Soham, Cambridgeshire, as the search for the 10-year-olds intensified. On several occasions, the theme of apparent guilt was raised, the jury was told.

Two detectives took a statement from Mr Huntley after he claimed to be the last known person to have spoken to Holly and Jessica. Detective Constable Andrea Warren said he had initially appeared calm and relaxed, then his manner changed. "He asked me why did I need to take a statement," she said. "He asked if he was a suspect."

Mr Huntley told her the girls approached him the evening they went missing while he was cleaning his dog, Sadie, outside his front door. After a brief conversation about his fiancée, Maxine Carr failing, he said the girls walked off.

"He seemed a little bit agitated. His hands got ever so clammy and he brushed them down the side of the chair," DC Warren told the court. During the conversation about his movements that evening he used the term "we". Despite the prosecution's claim that Ms Carr was in Grimsby until the following day, he "nonchalantly" told the officer and Detective Constable Jonathan Taylor that she was not in the house because she had popped out to look for a job.

The officers searched the "very, very clean" downstairs of his home, and the "sparse upstairs and messy bedroom", noting the lemon smell of cleaning fluid in the air.

DC Taylor told the court that they had forgotten to ask Mr Huntley to sign a search consent form so they returned two days later to sort out the paperwork. The officer noted that he looked red-eyed and tired.

"He said, 'You think I have done it. I was the last person to see them or to speak to them'." Then he started to cry," DC Taylor said. "I told him not to persecute himself and pull himself together. I told him other people had seen the girls in the area and in the High Street. It seemed to cheer him up a bit." Stephen Coward QC, for Mr Huntley, pointed out that the officer had not written his account until two weeks later. He asked why he had not picked up on Mr Huntley's alleged change of timings when being interviewed, and asked: "How long have you been a police officer?" DC Taylor said: "Twenty-nine years."

A neighbour, Stephen Fitchett, told the court that he was walking past Mr Huntley's house on his way to join searchers when he also spoke to the caretaker on 4 August. "He said the police had already searched his house and it makes you look guilty," he said. "I said, 'Why would you feel guilty if you have got nothing to hide?' He replied, 'It still makes you look guilty'."

The same evening several people noted that Mr Huntley appeared to be giving his red Ford Fiesta a thorough clean, the court was told.

Marion Clift, a neighbour of Ms Carr's mother, Shirley Capp, in Grimsby, told the court that she saw a "pale and shaking" Mr Huntley and a tearful Ms Carr looking into the boot of the Fiesta on 6 August in Grimsby. Mr Huntley had driven to collect Ms Carr.

The jury heard earlier that Mr Huntley had told one detective that he had seen a "dirty" red Ford Fiesta driving slowly around the Soham area the previous night. Later, a "relaxed" Mr Huntley approached special constables and reported seeing a man carrying what looked like a black bin-liner near the tennis courts between Soham Village College and St Andrew's primary school. "He indicated the person had run from the tennis courts and in the direction of a wooded area," said Special Constable Leslie Redhead.

Another of their group, now a constable with Bedfordshire police, noted the scratches on Mr Huntley's face. Detective Constable Russell Goldsmith said: "He [Mr Huntley] pointed out scratches which he said his dog did in play-fighting." The officer saw three scratches, unnoticeable until pointed out, about an inch long and running vertically along his jaw. Mr Coward suggested there was no such injury. DC Goldsmith said: "I know what I saw and I know what was pointed out to me."

Holly and Jessica were found dead in an isolated ditch next to Lakenheath air base, Suffolk on 17 August. Mr Huntley denies two counts of murder and Ms Carr has pleaded not guilty to two charges of assisting an offender and one of conspiracy to pervert the course of justice.

The trial continues.