Alice da Silva Aguiar, nine, Bebe King, six, and Elsie Dot Stancombe, seven, died in the attack in July last year.
DCI Jason Pye, who led the investigation, said no training course could have prepared his officers for the horror of what they saw.
Judge Mr Justice Goose ordered Axel Rudakubana to be removed from the dock shortly after the start of the sentencing hearing.
The 18-year-old’s disruptions meant he was not in court as the judge handed him one of the longest minimum terms on record.
Here is a timeline of what was known when about Southport killer Axel Rudakubana: Axel Rudakubana becomes known to a range of local agencies due to anxiety, social isolation and challenging behaviour.
Axel Rudakubana said 'I’m glad they’re dead' as he was held in a custody suite after killing three girls at a dance class, the court heard ...