Mr Davis said he had spoken to the boy earlier that day after he had returned to school following an incident the previous week when the school had gone into lockdown.
The jury has heard how, on 29 January two members of staff physically intervened in a dispute between two other students and the defendant had to be restrained as he tried to get involved.
Prosecutors said it was the defendant’s claim that one boy had a knife that led the school to go into lockdown, although the police who responded never found a weapon.
Harvey was not in school that day.
Mr Davis said he discussed this incident on the morning of the killing with the defendant, and asked him: “You’ve not brought anything in, have you?”
He said the boy replied: “No, no, no, no, nothing like that, I’m just happy to be back in school.”
Asked about Harvey, Mr Davis said: “I would describe him as a bit of a cheeky-chappie.
“He’s really funny, really likeable, always got a smile on his face.”