Vincent O'Dempsey is preparing to appeal against his convictions for the murders of Barbara McCulkin and her two daughters 43 years ago.
O'Dempsey was last month found guilty by a Brisbane Supreme Court jury of taking Mrs McCulkin, 32, and sisters Vicki, 13, and Leanne, 11, from their Highgate Hill home on the night of January 16, 1974 and killing them in bushland near Warwick.
In handing down a life sentence, Justice Peter Applegarth described O'Dempsey as "beyond redemption" and said he expected the 78-year-old to die in jail.
"You were the principal offender in each brutal killing," Justice Applegarth said.
Solicitor Terry O'Gorman confirmed on Thursday preparation was under way to appeal against the verdicts, with documents to be filed to the court at a later date.
Garry Dubois, who was found guilty in November 2016 of murdering the children but of Mrs McCulkin's manslaughter, is also appealing against his convictions.
Both men protested their innocence at their sentencing hearing on June 1, with O'Dempsey telling the court he was "completely innocent".
"I have never had the slightest reason to harm the three McCulkins in any way, nor did my co-accused," O'Dempsey said.