Child safety advocates Bruce and Denise Morcombe have been hailed by politicians for their inspiration and courage in the wake of what Prime Minister Tony Abbott has described as unimaginable sorrow.
The Morcombes have visited Parliament House in Canberra to promote Friday's 10th annual Day for Daniel, in honour of their murdered son.
Mr Abbott acknowledged the sorrow the couple faced in losing Daniel, who was 13 when he was abducted from a Sunshine Coast bus stop in 2003 and murdered by child sex offender Brett Peter Cowan.
"Nevertheless they have done something heroic," he said.
"They have turned the most awful tragedy into an opportunity to do some good and we thank them for the heroism that they've shown."
Opposition Leader Bill Shorten noted the English language had words for husbands and wives who've lost their partners and for children who've lost their parents.
"But we do not have a single word to describe parents who lose their children and I don't think any word can," he said.
Many MPs wore red ribbons and red T-shirt pins, the symbol of Day for Daniel.
Cowan was convicted in March and sentenced to life imprisonment for Daniel's murder, with a non-parole period of 20 years.