Alzen was a Srivani scientist who boarded the USS Voyager under cloak to conduct covert medical experiments on the crew in order to obtain data for the Srivani medical database.
After she was exposed by Seven of Nine, Alzen was captured and imprisoned in the brig. Alzen explained that the Srivani were conducting the experiments to get data to cure diseases that affected their race. Alzen believed that there was nothing wrong with what she and her team of scientists were doing. She matter-of-factly explained that there would be a few deformities, and a few deaths, but that she would share her findings with Captain Janeway. She also threatened to kill the crew if Captain Janeway refused her offer. Janeway refused and foiled their plan when she set Voyager on a direct course for the middle of a binary pulsar, which would have destroyed the ship with the aliens aboard. The Srivani's two ships detached themselves from Voyager and retreated, although one was destroyed. Voyager survived and The Doctor removed all the genetic tags from the crew. (VOY: "Scientific Method")