The Prime Sentinels were creations of Bastion and Operation:Zero Tolerance. Instead of being robots like their predecessors, the Prime Sentinels were cyborgs. Thus they could use the innate mental abilities of their human identity, including cunning and creativity. The first few Prime Sentinels were volunteers, recruited among the Friends of Humanity and other people feeling motivated against mutants. But their numbers were not enough and Bastion wanted a sizable army, not a hand full of people.
Bastion used Zero Tolerance funds to open secret facilities around the planet where people could be converted to Prime Sentinels against their will. Developing a technique which would replace their human persona with one of an obedient Sentinel. He started from Calcutta, India. Due to overpopulation it was thought that few would notice disappearances. Another facility was established in the desert of New Mexico, offering cures to severely handicapped people. They willingly undertook the process and were turned to sleeper agents. A third facility was created in Monkey River Town, Belize. People from all over the world "won" free trips to the tourist resort and were unwittingly turned into cyborgs during their vacation.
The Prime Sentinels served capably during Operation:Zero Tolerance but were left directionless when it was shut down and they lost contact with Bastion. Some regained their free will, other stayed in their Sentinel persona. Stryfe briefly took over control of the Belize facility and created Prime Sentinels loyal to him. He was defeated by an alliance of the X-Men and Lady Deathstrike. Currently the most prominent surviving Prime Sentinel is Karima Shapandar.
All Prime Sentinel units could shape-shift between regular human form and Sentinel hunter mode. Thus they could approach targets while not recognized as threats. They had enhanced human strength, reflexes and durability. They had force fields protecting them from damage and self-repair mechanisms which would restore both organic and technological parts to full health if given enough time. They could be destroyed if receiving sufficient damage to shut down their systems. They had scanning devices which could track down and analyze any given target. They were equipped with laser weapons, bio-blasts modified to the physiology of the target and cloaking devices. They used boot rockets for flight.
A few Prime Sentinels were chosen to become Omega Prime Sentinels, units with enhanced capabilities. These included vast data storage capacity, hologram projections and adaption to threats. They could also throw finger-knives and armor piercing darts.