An ongoing Associated Press investigation has uncovered deep, previously unreported flaws within the Bureau of Prisons over the last few years, including widespread criminal activity by employees, dozens of escapes, the free flow of guns, drugs and other contraband, and severe understaffing that has hampered responses to emergencies.

The prison on a forbidding island off San Francisco was operated at a prohibitive cost. Now, President Trump says it's time to substantially enlarge and rebuild Alcatraz as a federal penitentiary.

Experts say the federal government would have to overcome enormous hurdles to make the facility operational again.