Just a two-hour drive from Denver, on a 37-acre compound in the middle of Fremont County, sits America’s highest-security federal prison: the U.S. Penitentiary Administrative Maximum Facility—otherwise known as ADX.

The controversial penitentiary on the outskirts of Florence—a small, rural town once founded as a pass-through for coal-carrying trains in the 1800s)—first started housing inmates in 1994. Today, ADX is home to 361 of the country’s most high-profile criminals. Prisoners here—we’re talking serial killers, terrorists, mobsters, cult leaders, drug kingpins, and those deemed too violent to live among a general prison population—live in near-continuous solitary confinement. Inmates spend 23 or more hours a day isolated in soundproof, 7-by-12-foot cells outfitted with a single four-inch slit for a window. Due to these conditions, the ADX has been at the center of contentious debate about human rights and solitary confinement’s effect on mental health. As Robert Hood, a former warden of the ADX, told the New York Times in 2015, “this place is not designed for humanity.”

In fact, the decision by a London court in early 2021 not to extradite Julian Assange to American soil can be partially attributed to his possible assignment to ADX.  The judge, Vanessa Baraitser, said that her impression of the WikiLeaks founder’s mental state was “such that it would be oppressive to extradite him to the United States of America.” The ruling implied that 23-hour-a-day isolation would be too iron-fisted for someone exhibiting depressive and suicidal behavior. Assange is currently jailed in southeast London.

The last time ADX made headlines for a high-profile individual was in 2019, when Joaquín “El Chapo” Guzmán, the leader of Mexico’s Sinaloa drug cartel, was relocated to Colorado after being sentenced to life plus 30 years on international drug trafficking charges. With a propensity for violence and access to near-unlimited resources, El Chapo was an obvious candidate for the ADX. He’s twice escaped from maximum-security prisons in Mexico—his jailbreak from El Altiplano in the summer of 2015, in which he drove a motorcycle through a mile-long underground tunnel, is the stuff of movies. As was his recapture by Mexico’s marines in January 2016, which was preceded by a massive six-month manhunt, a deadly gunfight, and El Chapo slipping out of an escape hatch hidden behind a closet mirror.

No one has ever escaped the ADX (although there has been one homicide within its walls), which is why it’s been called “The Alcatraz of the Rockies.” Most prisoners get out only in death, via transfer to another facility or, in very few cases, if they live long enough to see their release date.

Here, we take a look at some of the most notorious (and dangerous) men detained in America’s toughest prison.

Editor’s note, 2/24/21: This article has been updated with new information. 

Terry L. Nichols

Domestic terrorist/Oklahoma City bomber, serving 161 consecutive life sentences  

Terry L. Nichols met Timothy J. McVeigh while the pair were serving in the U.S. Army in the late ’80s. They both became vehement anti-government conspiracy theorists, studied bomb making together at gun shows and, in 1995, the pair conspired to destroy the Alfred P. Murrah Federal Building in Oklahoma City. Their bombs ultimately killed 168 people, including 19 young children and babies. Nichols received 161 consecutive life sentences for his role in the bombing. McVeigh, who was ostensibly the mastermind behind the Oklahoma City bombing, was executed by lethal injection at USP Terre Haute in 2001.

Robert P. Hanssen

Soviet spy, serving 15 consecutive life sentences

Robert P. Hanssen was an FBI agent for 25 years (1976–2001). During that time, he sold thousands of classified documents to Soviet and Russian intelligence, pocketing at least $1.4 million by the time he was caught in 2001. Hanssen pled guilty to 14 counts of espionage and one of conspiracy to commit espionage, and was sentenced to 15 consecutive life terms. Hanssen’s treason was called “possibly the worst intelligence disaster in U.S. history” by William H. Webster, the chairman of the Commission for the Review of FBI Security Programs.

Ramzi Ahmed Yousef

One of the 1993 World Trade Center bombers; serving life plus 240 years

On February 26, 1993, a 1,300-pound nitrate-hydrogen gas bomb was detonated in the parking garage of the North Tower of the World Trade Center in downtown New York City, killing six people and injuring thousands. Yousef escaped to Pakistan after the attack and wasn’t apprehended until 1995, when he was sentenced to life plus 240 years, and told the courts he was “proud” of his identity as a terrorist. In all, seven people were known to be responsible for the WTC attack, though only six were caught. Abdul Rahman Yasin is still at large, and the FBI is offering up to $5 million for any information that leads directly to his arrest.

Richard Lee McNair

Master escapist, serving life but could be transferred to state prison

This Oklahoma man was convicted of murder, attempted murder, and burglary, for which he received two life sentences, but that’s not what would put him in ADX. It was McNair’s three successful escapes that would land him in semi-permanent solitary confinement. The first was in 1988, where he used lip balm as a lubricant to shimmy off his handcuffs while he was being held for questioning in a North Dakota county jail. An elaborate chase ensued, and he was caught, but that hardly deterred McNair. He escaped the North Dakota State Penitentiary again in 1992 and 2006, when he mailed himself out of prison and lived successfully on the outside until he was captured in 2007. The authorities then figured it was time to level up (literally).

Ted John Kaczynski

Domestic terrorist, aka the “Unabomber,” serving eight life sentences

Now 78-year-old Ted Kaczynski grew up in a Chicago suburb and was by all means a brilliant and prophetic student when he was admitted to Harvard University and took part in a three-year ethically questionable psychological study that some speculate may have attributed to his later extremist beliefs and behavior. He went on to earn a doctorate in mathematics and, soon after, in 1971, he began his hermetic life in a secluded cabin in Montana. It is here he would pen his famous manifesto, “Industrial Society and Its Future,” and begin a 17-year effort to sabotage what he called the industrial-technological system. In all, he mailed 16 homemade bombs that ultimately killed three people before he was found in 1996. Kaczynski was charged with three counts of homicide, 10 federal violations related to bombs, and was sentenced to eight lifetimes in prison.

Michael Swango

Serial killer nicknamed “Dr. Death,” serving three consecutive life terms

Michael Swango (born Joseph Michael Swango) was a physician who spent most of the 1980s and ’90s using his medical license to poison patients (and, sometimes, colleagues). Despite thoroughly creeping out plenty of people by the time he earned his degree from Southern Illinois University School of Medicine (including being caught “faking” checkups during OB-GYN rotations), Swango secured an internship at what was then known as the Ohio State University Medical Center in 1983. This is where his prolific career as a serial killer would purportedly begin. It is believed that Swango murdered more than 60 people—often by poisoning them with arsenic or intentionally overdosing them with something they were prescribed—though he could only be charged with four homicides. Swango was sentenced to life in prison in 2000.

Dzhokhar A. Tsarnaev

Terrorist, aka the Boston bomber, life in prison

Dzhokhar Tsarnaev and Tamerlan Tsarnaev, two brothers of Chechen descent, were raised in Kyrgyzstan before immigrating to Cambridge in the 1990s. The brothers were radicalized by al-Qaida and built two pressure-cooker bombs that they planted at the 2013 Boston Marathon; the explosion killed three people and injured more than 250 others. Dzhokhar and Tamerlan (19 and 26 years old at the time) at first evaded capture and, three days later, killed Massachusetts Institute of Technology police officer Sean Collier while trying to steal his gun; Tamerlan was shot and killed by police in a chaotic and violent chase less than 24 hours later. During his 2015 trial, Dzhokhar was found guilty of 30 charges, including using a weapon of mass destruction, and was sentenced to death by lethal injection. In July 2020, a court overturned Dzhokhar’s death sentence.

In July 2020, a federal appeals court overturned Dzhokhar’s death sentence—a decision that could be reviewed by the U.S. Supreme Court sometime in 2021.  The confiscation of items he bought from the prison commissary and limited access to showers were cited in the complaint.

Larry Hoover

Chicago gang leader, serving six life sentences 

A transplant from Mississippi to Chicago, Larry Hoover got involved in gangs at just 13 years old. He was a member of Supreme Gangsters, which later merged with a rival gang to become the Black Gangster Disciple Nation. Hoover, aka “King Larry,” commissioned the killing of a drug dealer named William Young, who he suspected was stealing drugs and money from the Gangster Disciples in 1973, and was sentenced to 150 to 200 years. However, a federal investigation is said to have uncovered decades of Hoover’s gang leadership in prison, which included overseeing its lucrative business and more than 30,000 gang members throughout 35 states; in 1995, Hoover was convicted of drug conspiracy and extortion, and moved to the ADX.

In 2018, musician and fellow Chicagoan Kanye West asked President Donald Trump to pardon Hoover. That same year, Trump signed the First Step Act, for which West and his estranged wife Kim Kardashian lobbied, into law. The First Step Act addresses superfluous and discriminatory drug sentencing and aims to improve prison conditions; it also resulted in the release of 3,100 inmates for good behavior. Federal agents urged against applying any clemency to Hoover, however, who is suspected of continuing to pull strings in the gang world using coded messages sent from prison. In August 2020, the Chicago Tribune printed an editorial titled, “Keep Larry Hoover in federal supermax. Chicago’s safety is at stake.”

Mamdouh Mahmud Salim

Al-Qaida cofounder, serving a life sentence

In 1988, Mamdouh Mahmud Salim attended a meeting with Osama bin Laden and a roundtable of others to discuss starting a terrorist organization that became known as al-Qaida. The Sudanese terrorist’s suspected crimes are innumerable, but he was arrested in Germany in 1998 for his role in the U.S. embassy bombings in Kenya and Tanzania that same year. He was sentenced to 32 years but, after stabbing a prison guard in a botched escape attempt, was resentenced to life without parole in 2010.

Richard C. Reid

Shoe Bomber, serving three consecutive life sentences

Also an al-Qaida member, British-born Richard Reid is who you can thank for having to take off your shoes everytime you go through TSA. In late 2001, Reid packed his shoes with explosives and boarded an American Airlines flight heading from Paris to Miami; thankfully, the homemade bombs did not go off. He was tackled by passengers and arrested after an emergency landing at Logan International Airport in Boston. He was charged with eight counts of terrorism, and received three life sentences, plus 110 years sans parole.

Dwight York

Pedophile and cult leader, serving a life sentence

Dwight York, aka Malachi Z. York, founded the Nuwaubian Nation in the late 1960s. The group grew from a seemingly benign black Muslim group into a black nationalist cult with wildly inconsistent and bizarre ideas, including the belief in UFOs, hatred of white people, and worshipping Egypt. (A compound styled as an ode to Ancient Egypt was even built in Georgia by some followers of the group now known as the United Nuwaubian Nation of Moors.) York’s motivations and influence are winding and convoluted but, in short, he was a conman and cult leader who used his power to systematically abuse children. In the early 2000s, he was convicted of racketeering and child molestation (14 children testified against him), and was subsequently sentenced to 135 years in prison.

In 2018, York filed a three-page lawsuit against the Macon County police department, the state of Georgia, and the FBI, among others, seeking $2 billion in damages. He argued that as an Indigneous person, the U.S. government has no jurisdiction over him.

Eric R. Rudolph

Olympic Park bomber, serving two life sentences

Born and raised in the southeast, Eric Rudolph spent time as a teenager at a compound in Missouri for members of the Church of Israel, a Christian denomination born of the Latter Day Saint movement. His time there influenced his radicalization: Rudolph, a high-school dropout and U.S. Army veteran, would go on to commit a series of bombings that were meant to be political attacks on “global socialism” and the “homosexual agenda” among other things. In 1996, Rudolph became infamous when he bombed Centennial Olympic Park in Atlanta during the Summer Olympic Games, killing one spectator and injuring more than 100 others. Despite calling the police to forewarn of the bombing, law enforcement didn’t know who was responsible, and Rudolph went on to commit three more bombings in 1997: at abortion clinics in Georgia and Alabama, and a lesbian bar in Atlanta. Rudolph was one of the FBI’s most-wanted criminals until he was apprehended in North Carolina while dumpster diving in 2003. He was sentenced to two life terms.

Jerilyn Forsythe
Jerilyn Forsythe
Jerilyn Forsythe is a freelance writer and editor, and 5280's former digital associate editor. Follow her on Instagram or Twitter @jlforsyt.