The parents of the Southport killer struggled to deal with his violent outbursts, especially as he grew "older and stronger", the inquiry into last year's stabbings in the town has heard.
It comes on the day that police said they didn't arrest Axel Rudakubana two years before his attack, when he was found on a bus with a knife and instead treated him as a vulnerable person.
Alice da Silva Aguiar, nine, Bebe King, six, and Elsie Dot Stancombe, seven, were stabbed to death at a Taylor Swift-themed dance class on 29 July last year by Rudakubana, then aged 17.
The inquiry at Liverpool Town Hall heard about a series of 999 calls, in the first of which, on 5 November 2021, his mother told Merseyside Police that her son had been smashing the house up, throwing things around and throwing th