US to put four prisoners to death this week as Trump pushes for executions

Killings scheduled in Alabama, Florida, Oklahoma and South Carolina despite concern over states' methods

Four executions are scheduled across the US this week, marking a sharp increase in killings as Donald Trump has pushed to revive the death penalty despite growing concerns about states' methods.

Executions are set to take place in Alabama, Florida and South Carolina. A fourth, scheduled in Oklahoma, has been temporarily blocked by a judge, but the state's attorney general is challenging the ruling.