(WASHINGTON) — A Kansas man has admitted to murdering his longtime girlfriend on a cruise ship off the coast of Florida last year, federal prosecutors said. Eric Duane Newman, 55, of Topeka, Kansas, pleaded to guilty in federal court on Thursday to one count of second-degree murder with malice aforethought for the January 2018 death of his 50-year-old girlfriend, Tamara Tucker, according to a press release from the U.S. Department of Justice. Newman and Tucker boarded the Carnival Elation cruise ship in Jacksonville, Florida, on Jan. 18, 2019, for a round-trip voyage to the Bahamas. The couple was staying in a cabin room on the vessel’s 13th deck, prosecutors said.Newman admitted during his plea hearing that they argued in their room late that night. Newman said he strangled Tucker and pushed her over the balcony railing of their cabin room, causing her to fall onto the 11th deck just after midnight on Jan. 18. Tucker died from blunt force trauma caused by the fall, prosecutors said. The cruise ship was sailing in international waters at the time, about 30 nautical miles from New Smyrna Beach, Florida. Carnival Cruise Line said in a statement the day after Tucker’s death that “the ship’s medical team responded immediately, but, unfortunately, she passed away.”Tucker, a native of Lawson, Missouri, had been a social work professor at Park University in Parkville, Missouri, from 2012 to 2017. Her obituary described Newman as her “partner and longtime love.” Newman was arrested for Tucker’s murder nearly eight months after her death. His sentencing is scheduled for March 18. Copyright © 2019, ABC Audio. All rights reserved.