He will be the third person executed by firing squad in Utah - or anywhere else in the U.S. - since the death penalty was reinstated in 1976, AP reports.
Gardner chose the firing squad in April, politely telling a judge, "I would like the firing squad, please." Neither he nor his attorneys have said why.
Critics decry the firing squad as a barbaric method that should have been relegated to the dustbin of the frontier era.
"The firing squad is archaic, it's violent, and it simply expands on the violence that we already experience from guns as a society," Bishop John C. Wester, of the Roman Catholic Diocese of Salt Lake City, said during an April protest.
The diocese is part of a new coalition pushing for alternatives to capital punishment in Utah.
SIC: CTHUSA