At a federal prison in rural Virginia, more than 50 prisoners say they've been abused. But when they try to file a complaint — they're stopped, often by the same guards they say are abusing them.

Investigators said warden Andrew Ciolli should have stopped abuse of prisoners. He faced disciplinary action. Now he's the director of a federal center that teaches others how to run prisons.

He was tasked with ending abuse at a federal penitentiary in Illinois but says his own staff and Bureau of Prisons officials blocked his efforts.

More than 120 prisoners held at a special unit in Thomson Penitentiary reported mistreatment, a Washington Lawyers' Committee report says.

The Marshall Project asked people in prison to track their earning and spending — and bartering and side hustles — for 30 days. Their accounts reveal a thriving underground economy behind bars.

In Georgia, county courts have contracted with private probation companies to collect fines from offenders. People are sometimes jailed for not being...