Argentina's Navy has officially abandoned hope of finding the ARA San Juan intact and its 44 crew members alive, the Wall Street Journal reports. The U.S. joined a multinational search for the submarine after it disappeared on Nov. 15. Authorities now believe a battery failure caused an explosion on board the vessel — killing all crew members and sending the wreckage to the ocean floor.

There was a glimmer of hope in the search on Nov. 20 when Argentine ships said they detected sounds that may have been a distress signal coming from the submarine. The navy is now conducting an internal investigation into the events leading to the vessel's apparent destruction.