A human-built version of the Martian Resurrection Chamber.
The Martian Resurrection Chamber is a piece of technology designed to revive a deceased subject by cloning it and reunite it with its soul. The Chamber is capable of operating with even trace amounts of DNA; Mike Warner was brought back to life using nothing more than a blood-stained shirt, while David Walkerton was resurrected using more... intimate genetic samples.
Growing a cloned body to maturity can take several months; curiously, the resulting body is "mirrored" compared to the original subject's.
Most of the Martians' resurrection technology was wiped out when Ultra Car destroyed the Martian mothership, but Lith was able to collect enough components for Joe Rosenthal to build a functioning Resurrection Chamber at a secret location in Denver, Colorado. After reviving Walky (AKA "Subject Alpha"), the Chamber continued to be used to resurrect agents killed in the line of duty; in Joyce and Walky!, it was revealed that there's quite the waiting list.
Blueprints for this technology were later leaked by Joyce Brown to an unnamed company, and may be responsible for the resurrections of Ronald Reagan, Franklin Delano Roosevelt, and Jeshua Ben Joseph.