A detective accused of concocting a false alibi for himself with the aid of a friend has denied lying to police.
Brian Stevens and Louise Austin are on trial at the Old Bailey
Det Con Brian Stevens said he may have "made a mistake" about where he was on the date pornographic material was allegedly downloaded on to his laptop.
The Soham officer had told police he was 100 miles away from his laptop when the images were made on 9 June 2002.
In a later statement, heard by the Old Bailey on Tuesday, he said he may have muddled dates, but not intentionally.
'Never asked for alibi'
No evidence was offered against Mr Stevens, 43, at Snaresbrook Crown Court in August last year after he was charged over the images.
He and Louise Austin, a 32-year-old case officer for
the Crown Prosecution Service, said he was at her Cambridgeshire home - a two-hour drive from Goring-on-Thames, Oxfordshire, where the downloading took place.
The prosecution claims mobile phone records show the detective, who was a liaison officer to the family of Soham murder victim Jessica Chapman, was elsewhere.
Mr Stevens and Miss Austin both deny conspiring to pervert the course of justice.
In a statement Mr Stevens told police: "I have never asked her (Miss Austin) to lie on my behalf and, in particular, to provide an alibi for the period 8 June and 9 June.
"I did drive from Goring to see Miss Austin at her address.
"I believe that this happened on the 8th/9th June 2002."
He said he had seen the mobile phone records and added: "I accept I may have made a mistake as to these dates. If I did, the mistake was not with the intention of perverting the course of justice.
"The date of 8/9 June came from her (Miss Austin's) recollection, not my own."
The images were alleged to have been downloaded to a laptop computer at a police officers' rehabilitation centre in Goring-on-Thames.
The court was told on Monday by telecommunications expert David Bristowe that Mr Stevens' mobile phone had registered itself as in use with cell sites around Goring-on-Thames eight times on 8 June and once on 9 June.
"There is no chance whatsoever that phone was in the Cambridgeshire area," he told the court
The case continues.