On Monday, the Russian Federal Space Agency confirmed the five geckos were discovered dead when their landing apparatus returned to Earth just prior to 1:20 p.m. Moscow time.
"According to the preliminary information, it became clear the geckos froze," an anonymous member of the Russian scientific community claiming to be involved with the project told local reporters.
"Most likely, this happened due to a failure of the equipment meant to ensure the temperature of the box with the animals. The geckos could have died at any stage of the flight, and it's impossible to judge when based on the animals' mummified remains."
Although the geckos appear to have froze to death, "as usually happens in such instances, [RFSA] will soon appoint an emergency commission to find out these animals' cause of death."
The late coital lizards, one male and his four-female harem, first gained international attention when Russian scientists lost contact with their vessel in July.
HBO's John Oliver launched an apparently successful hashtag campaign on Twitter, demanding Russian President Vladimir Putin and his scientists #GoGetThoseGeckos, enlisting Buzz Aldrin, Patrick Stewart and Timm Gunn among other notable celebrities to encourage action on the lizards' behalf. The geckos were recovered in August, just a month before their untimely demise.
It remains unclear if the conditions of their disappearance enabled the geckos' cause of death. Oliver has yet to release an official statement about the incident.