TAIPEI, Taiwan—The owner of a construction truck that caused Taiwan’s worst rail accident in decades, killing 48 people, apologized in tears while being led away from his home by police on Sunday. The unmanned truck’s emergency brake was not properly engaged, according to the government’s disaster relief center. An investigation is underway as to how exactly Lee Yi-Hsiang’s vehicle slid down onto the tracks Friday from a nearby construction site on the mountainous coast of eastern Hualien county. The truck was hit by a passenger train carrying 494 people, which derailed just before entering a tunnel, crushing many passengers inside the mangled train carriages. The death toll was revised down to 48 on Sunday, after rescuers initially said 51, then 50 people were killed. The changes came after some body parts were found to belong to one individual, a spokesperson for the Central Emergency Operation Center said. At least 198 …