GUATEMALA CITY — Guatemalan President Alvaro Colom has vetoed legislation that would have reinstated capital punishment while giving the president the power to commute death penalty sentences. Colom vetoed a similar law two years ago. He said Thursday that his government doesn’t think the death penalty helps improve security. While reinstating the death penalty, the vetoed measure would have given Guatemala’s president the authority to commute a prisoner’s death sentence to a prison term of up to 50 years. Nineteen Guatemalan prisoners have been caught in a death row limbo since the country’s high court suspended executions in 2002. It ruled that presidential reprieves on death penalty cases were unconstitutional.