Software on an Aberdeen doctor's computer could have been used to cover evidence of downloading child pornography, a trial has heard.
Douglas Harris, 29, denies taking, permitting to be taken or making indecent images, as well as being in possession of pictures.
Forensic analyst Allan Friel-Myles told Aberdeen Sheriff Court he managed to recover 371 files.
Mr Harris has lodged special defences of incrimination and alibi.
Mr Friel-Myles said he was asked to examine Mr Harris' computer programmes.
Depute fiscal Neil Shand asked: "Would you accept that programmes of this nature are commonly used to cover tracks?"
He replied: "Yes."
Asked how the programme worked, he replied: "It changes file names and essentially removes the files from the computer."
However, he said the programme was marketed for people who wanted to clean up their computer to speed up their processor.
He added: "In the case the accused is a doctor. He may have the desire to delete confidential information.
"I have software on my own machine set to run every couple of days. I have found that helps maintain performance on my computer, run in combination with anti virus software."
The offences are alleged to have happened between 2004 and 2006.
The trial was adjourned for final submissions until Monday.