PYEONGTAEK, South Korea — Investigators let media have a look at the wreckage of the Cheonan on Wednesday, the day before South Korea was to formally announce that a North Korea torpedo sank the South Korean patrol ship. The wreckage of the March 26 sinking was retrieved from the Yellow Sea near the maritime border between the two Koreas and hauled to South Korea’s Second Fleet Command base in Pyeongtaek. Yoon Duk-yong, an investigator with the Korea Advanced Institute of Science and Technology, told reporters Wednesday that evidence from the recovered pieces of the ship points to a torpedo attack....