Kreege was a male Terran, a member of the Imperial Starfleet working as a doctor, who worked in the Terran part of the Scavenger base in the 24th century.
Kreege interrogating/torturing Telsia
He was trying to interrogate Telsia Murphy in sickbay, after she had been captured when she stole isodesium. Ensign Alexander Munro/Alexandria Munro, disguised as a member of the Terran crew, infiltrated the sickbay and Doctor Kreege asked Munro to bring him the blue hypospray with Veritrax 12. Munro entered the lab and took the red hypospray with Solinol instead, and knocked out the doctor. (VOY video game: Elite Force)