The Divide Universe Series by Sandra Bard

Nullands: Sections of a series of planets sealed off by an energy barrier, called the Divide, filled with danger, where technology does not work. Tarn is part of the Death Squad, a criminal given a second chance by agreeing to risk his life over and over again in the Nullands. His latest mission is the kind he usually avoids: babysit an inexperienced lab tech while they hunt down the dangerous creature that escaped a research lab... moreNullands: Sections of a series of planets sealed off by an energy barrier, called the Divide, filled with danger, where technology does not work. Tarn is part of the Death Squad, a criminal given a second chance by agreeing to risk his life over and over again in the Nullands. His latest mission is the kind he usually avoids: babysit an inexperienced lab tech while they hunt down the dangerous creature that escaped a research lab. Calvin is the lab tech given the unenviable task of hunting down the creature that escaped his lab, after it killed his friend and five others. An assignment he mostly landed for refusing to sleep with his boss, he knows damn good and well he's being sent to die. What he doesn't expect is Tarn, or how far he's willing to go to survive. less

When Commander Michele is murdered, the duty of managing the exploration base falls to Izaak. But Science Division doesn't want him in authority, his second in command is transferring out, and the inspector sent to investigate the murder is someone Izaak would much rather have never seen again. All in all, he'd rather be fighting monsters behind the Divide.