lesley jonathon cameron was just 19 when he committed the crimes .
he bludgeoned and stabbed maureen , 67 , and tamara horstman , 26 .
he entered their perth home in broad daylight in december 2013 .
he also raped tamara but it is not known if she was alive or dead .
cameron described himself at the time as a ` walking time bomb '
claimed he had taken ice and speed on the day of the murders .
tamara 's twin brother said ` no sentence will ever be long enough '
justice heenan said ` it shows the insecurity and vulnerability of everybody in the community to random crime '