“The Dirty Dozen” opened in movie theaters nationwide on June 15, 1967 with a popular Texas-born singer in his first serious role.

Trinidad Lopez III inherited his musical talent and stage presence from his father, who was a singer, dancer, actor and gifted musician in his hometown of Moroleon, Mexico. He and his wife Petra crossed the Rio Grande in the mid-1930s as undocumented immigrants and worked hard to make a new life for themselves in Dallas.

The third Trinidad, who like his fat...