This is the complete Extensis Vitae series, books 1-4.
Michael Reznik is a soldier who wakes up in a mysterious underground bunker, with a technologically advanced body he doesn't recognize. The people around him have cast aside fighting and warfare. They haven't needed them--until now.
Reznik is charged with tracking down a band of ruthless killers and finding a kidnapped doctor. He finds himself honor-bound to do what is right for the people who brought him back from the dead. A peaceful people are depending on him to do what is right. Can he live up to their expectations, even when he finds out that his new body has an expiration date?
Extensis Vitae is a gritty, post-apocalyptic science fiction adventure.
Great read! The story is believable and does not expect the reader to have any technical knowledge in order to accept the key themes ...