Miss Mallett said further examination of his phone revealed he had engaged in sexual conversation with a 15-year-old girl, who could not be traced.
Keogan admitted being sexually attracted to the girl, but claimed it was because of the way she looked rather than due to her age.
When he was initially interviewed he confirmed failing to disclose two internet user names, but said police would find no indecent images of children.
Fluet was arrested on suspicion of internet sexual exploitation of a child and criminal attempt soliciting for child prostitution.
"Any time someone asks to meet with a child under the age of 15 for sex they’ve committed a crime.
Durham Crown Court heard he was subject to home visits by a supervising police officer and a probation officer.
Miss Mallett said it subsequently emerged that Keogan met a woman through an internet dating site, accessed using a name he had not previously declared to police.
Fluet is Harris’ 55 arrest this year, the third arrest off Mocospace.