LONDON — A 19-year-old British man who shot and killed his mother and two younger siblings and who wanted to carry out a high-profile school shooting has been told he will not be eligible for parole for at least 49 years.

At the sentencing hearing at Luton Crown Court on Wednesday, Justice Bobbie Cheema-Grubb said she had considered handing Nicholas Prosper a full life order in prison but opted against that given his age — he was 18 at the time of the shootings — and the fact that he had pleaded guilty,

Last month, Prosper admitted at a hearing to murdering his mother Juliana Falcon, 48, and his 13-year-old sister Giselle Prosper and 16-year-old brother Kyle Prosper at the apartment the family shared in Luton, Bedfordshire, on Sept. 13.

The judge said Prosper had wanted to emulate and outdo the U.S. school massacres at Sandy Hook in Dec. 2012 and Virginia Tech in April 2007.