Edgar Martinez's father borrowed money last year from a friend in Antioch and paid for the 17-year-old to come north from Mexico. The teen worked in Bay Area housing construction, sending money to his mother and brother in Michoacan. But late Sunday night, a gunman wildly sprayed a dozen or more bullets into the small apartment building on West 20th Street where the father and son lived with three or four cousins. One of the rounds passed through the wall and killed Martinez as he slept next to his father, whom neighbors said had cried and begged his son to...