Michael Tranter said the high court battle over the legality of whole-term prison sentences for the worst murder cases had brought his own family tragedy back into sharp focus.
Now that it has been declared legal to impose sentences which mean murderers die in prison, Mr Tranter said the same penalty should apply to the man who killed his family.
Sarah-Jane, 17, her 16-year-old sister Anne-Marie and their brothers Steven, 14, and Craig, 13, along with their mother Lesley, were killed by their stepfather Lee Ford in September 2000.
Ford was given five life sentences and told he would serve a minimum of 35 years before being considered for parole.
But, crucially, he was not sentenced to a whole-life term, which means he could be released in the future.
“I can’t get closure,” said Mr Tranter, of Newdale, Telford. “I have got a thing in my head that says he probably won’t ever come out, but I would rather know that for sure.