Harrison Geier told the Australian Broadcasting Corp. group members want an opportunity to give statements in the case.
Their request to deliver evidence via a video link from Australia has been rejected by a Peruvian judge and the group has been ordered to return to the country.
Vacationers Jessica Vo, brothers Hugh and Tom Hanlon, Andrew Pilat, Sam Smith and Greier are accused of pushing doorman Lino Rodriguez Vilchez out the window of an apartment in Lima last year.
His death was originally ruled a suicide but investigators reopened the case after a public campaign by the doorman's brother. Wimber Vilchez.
The lawyer for the six Australians has indicated another appeal will be filed before his clients go to Peru.