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Just a two-hour drive from Denver, on a 49-acre compound in the middle of Fremont County, sits America’s highest-security federal prison: U.S. Penitentiary Florence Administrative Maximum Facility.
Colloquially known as ADX, it’s the only federal supermax prison in the country, and no one has ever escaped the “Alcatraz of the Rockies.” Opened in November 1994, the facility sits on the outskirts of Florence, a small town in Fremont County (aka Colorado’s Correctional Capitol). As of July 2024, ADX incarcerates 335 men convicted of federal crimes. In other words, these inmates aren’t your white-collar criminals; we’re talking serial killers, terrorists, mobsters, cult leaders, drug kingpins, and offenders who have proven themselves adept at escape, prone to violence, or otherwise unreformable.
Many ADX prisoners live in near-continuous solitary confinement inside a soundproof, 7-by-12-foot cell—a controversial policy that prison reform advocates have decried. There is a single four-inch slit for a window; a bed, desk, and stool made of poured concrete; and stainless steel sink-and-toilet combo. Pending good behavior, prisoners can earn 10 or more hours per week handcuffed outside of their cells in a caged confinement or a concrete pit (similar to an emptied swimming pool). Up to four 15-minute phone calls are allowed per month, and visitation rights are significantly restricted, if allowed at all.
The average American might not be aware of ADX, but the institution often makes front-page news because you’ve probably heard of some of its most infamous residents. Below, we highlight 16 of the most notorious felons who have been detained in America’s toughest prison.
Jump Ahead:
- Joaquín “El Chapo” Guzmán Loera
- Terry Lynn Nichols (Oklahoma City bomber)
- Dzhokhar Tsarnaev (Boston Marathon bomber)
- Larry Hoover
- Richard C. Reid (shoe bomber)
- Eric R. Rudolph
- Zacarias Moussaoui
- Michael J. Swango
- Ramzi Ahmed Yousef and Mahmud Abouhalima
- Dwight York
- Umar Farouk Abdulmutallab (underwear bomber)
- Abu Hamza
- Mamdouh Mahmud Salim
- Ted John Kaczynski (Unabomber)
- Robert P. Hanssen
Joaquín “El Chapo” Guzmán Loera
- Known for: Leading the Sinaloa Cartel
- Sentence: Life plus 30 years
Some might say El Chapo is the Houdini of hard time. Before being sent to ADX, the longtime leader of the Sinaloa Cartel had escaped from Mexican maximum security prisons twice. First, he bribed prison guards at Jalisco’s Puente Grande in 2001, but his jailbreak from El Altiplano in the summer of 2015 is the stuff of movies. El Chapo fled the facility on a motorcycle via an underground tunnel and led law enforcement on a six-month manhunt, complete with a deadly gunfight and the drug king slipping out of an escape hatch hidden behind a closet mirror. The Mexican Marines finally recaptured him in January 2016 near the town of Juan José Río in northern Sinaloa.
Now serving a life sentence plus 30 years in ADX Florence for 10 charges related to narcotics trafficking, money laundering, and weapons, El Chapo continues to make headlines. In early 2023, he sent a letter—described by one of his attorneys as an “SOS”—to Mexican President Andrés Manuel López Obrador requesting to complete his sentence in Mexico because his treatment in Colorado was “psychological torment,” CBS reported. In March 2024, El Chapo wrote another letter to the federal judge who sentenced his case back in 2019 to request visitation rights with his wife (who was released from jail after serving time for helping run the billion-dollar drug operation) and twice-a-month 15-minute phone calls with their twin daughters. His request was denied in April.
Terry Lynn Nichols
- Known for: Oklahoma City bombing
- Sentence: 161 consecutive life terms
Terry Lynn Nichols met Timothy J. McVeigh while they were serving in the U.S. Army in the late ’80s. The pair became vehement anti-government conspiracy theorists, studied bomb-making together at gun shows, and plotted to destroy the Alfred P. Murrah Federal Building in Oklahoma City. Their bombs, which McVeigh parked outside of the building and detonated on the morning of April 19, 1995, ultimately killed 168 people—including 19 children and babies—and injured hundreds of others.
Nichols received 161 consecutive life sentences for his role in the bombing. McVeigh, who was judged to be the mastermind behind the Oklahoma City bombing, was executed by lethal injection at USP Terre Haute in 2001.
Dzhokhar A. Tsarnaev
- Known for: Boston Marathon bombing
- Sentence: Death
Dzhokhar Tsarnaev and Tamerlan Tsarnaev, two brothers of Chechen descent, were raised in Kyrgyzstan before immigrating to Cambridge, Massachusetts, in the 1990s. The brothers were radicalized by al-Qaida and built two pressure-cooker bombs that they planted near the 2013 Boston Marathon finish line. The explosion killed three people and injured more than 260 others.
Dzhokhar and Tamerlan (19 and 26 years old, respectively, at the time) initially evaded capture and, three days later, killed Massachusetts Institute of Technology police officer Sean Collier while trying to steal his gun. Less than 24 hours later, Tamerlan was shot and killed by police in a chase. Dzhokhar was discovered hiding in a Watertown resident’s boat and later found guilty of 30 charges, including using a weapon of mass destruction. He was sentenced to death by lethal injection.
As of March 2024, the bomber, who is imprisoned at the ADX, is awaiting the results of an investigation into his 2015 trial. A lower court will evaluate whether two jurors should have been disqualified for bias, but in the meantime, his sentence stands.
Larry Hoover
- Known for: Founding Chicago’s Gangster Disciples
- Sentence: Six life terms
A transplant from Mississippi, Larry Hoover got involved with gangs in Illinois at just 13 years old, later becoming synonymous with Chicago’s largest and most well-known gang: the Gangster Disciples. Hoover, aka “King Hoover,” is credited as a co-founder of the Gangster Disciple Nation, a sprawling organized crime ring. In 1973, he commissioned the killing of a drug dealer named William Young, who he suspected was stealing drugs and money from the Gangster Disciples, and was sentenced to 150 to 200 years in prison. 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 members throughout 35 states. In 1997, Hoover was convicted of drug conspiracy and extortion and transferred to ADX Florence—in an effort to prevent him from conducting any criminal activity with the outside world.
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 then-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 December 2021, rappers West and Drake threw a “Free Larry Hoover Benefit Concert” at the LA Memorial Coliseum which was livestreamed on Amazon Prime. The concert would prove ineffective; Larry Hoover remains in ADX serving six life sentences.
Richard C. Reid
- Known for: Attempted “shoe bombing”
- Sentence: Three consecutive life terms
Also an al-Qaida associate, British-born Richard Reid is the reason travelers must remove their shoes at airport security checkpoints. In December 2001, Reid packed his shoes with explosives and boarded an American Airlines flight heading from Paris to Miami; thankfully, the homemade bombs didn’t 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 without parole.
Eric R. Rudolph
- Known for: 1996 Atlanta Olympics bombing
- Sentence: Two life terms
Born and raised in the southeast, 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 Saints 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 July 1996, Rudolph 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 (yes, Rudolph called the police twice about the bomb), law enforcement officials didn’t know who was responsible, and Rudolph went on the run. He committed three more bombings throughout 1997 and 1998: He attacked an abortion clinic in Georgia; a lesbian bar in Atlanta; and an abortion clinic in Alabama, which killed Birmingham police officer Robert Sanderson. 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.
Zacarias Moussaoui
- Known for: Being a 9/11 conspirator
- Sentence: Life without the possibility of parole
Zacarias Moussaoui was arrested in August 2001 when, after several months of aviation school, his flight instructor reported his suspicious behavior to the FBI. Reportedly, Moussaoui asked nonsensical questions, only expressed interest in how to liftoff and land a plane, had no background in aviation nor a private pilot’s license, and paid for the $6,300 course in cash.
Moussaoui, who was born to Moroccan parents in France, was charged in December 2021 for six counts of conspiracy to commit acts of terrorism, aircraft piracy, and more for his involvement in the preparation for the September 11, 2001, attack that killed 2,977 people. During the trial, he claimed he and Richard Reid, the shoe bomber, were supposed to fly a fifth plane into the White House. Moussaoui is, as of June 2024, the only person convicted of a crime in connection with 9/11 in a U.S. court.
Michael J. Swango
- Known for: Serial murder
- Sentence: Three consecutive life terms without parole
Joseph Michael Swango was a physician who spent most of the 1980s and ’90s using his access to patients during medical school and beyond 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, 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 three life terms in prison in 2000.
Ramzi Ahmed Yousef and Mahmud Abouhalima
- Known for: 1993 World Trade Center bombings
- Sentence: Life plus 240 years and 67 years, respectively
On February 26, 1993, a urea nitrate-hydrogen gas bomb weighing more than 1,000 pounds 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 more than a thousand. Yousef escaped to Pakistan after the attack and wasn’t apprehended until 1995, when he was sentenced to life plus 240 years in ADX, and told the courts he was “proud” of his identity as a terrorist. Egyptian nationalist Mahmud Abouhalima was considered a co-conspirator and is currently serving a 67-year sentence in Colorado; his release date would put him at 98 years old. The two do not interact per the facility’s protocol.
In all, seven people were known to be responsible for the 1993 World Trade Center 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.
Dwight York
- Known for: Founding the Nuwaubian Nation cult
- Sentence: 135 years
Dwight York, aka Malachi Z., founded the Nuwaubian Nation in Brooklyn in the late 1960s. Originally a Black Muslim group, it quickly transformed into a Black nationalist cult with wildly inconsistent and bizarre ideas, including belief in UFOs, hatred of white people, and idolatry of Egypt. Some followers of the group, now known as the United Nuwaubian Nation of Moors, even built a compound styled as an ode to Ancient Egypt in Georgia.
York’s motivations and influence are convoluted but, in short, he was a con artist 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 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 Indigenous person, the U.S. government has no jurisdiction over him.
Umar Farouk Abdulmutallab
- Known for: Attempted “underwear bombing”
- Sentence: Four life terms plus 50 years
Umar Farouk Abdulmutallab, the youngest child of a prominent Nigerian banker, became radicalized while studying Arabic in Yemen, where he completed training under al-Qaida in the Arabian Peninsula.
On December 25, 2009, Abdulmutallab boarded a flight from Amsterdam to Detroit with a bomb sewn into his underwear. The six-inch explosive device burned Abdulmutallab but failed to properly detonate; if it had, it likely would have killed all 289 people aboard the plane. He was convicted of eight counts of federal crimes, including attempted use of a weapon of mass destruction and attempted murder, in 2012 and sent to ADX.
Abu Hamza
- Known for: Being a co-conspirator in the 1998 Yemen kidnappings
- Sentence: Life
Abu Hamza was born in Alexandria, Egypt, in 1958 and moved to London where he espoused radical views as an imam at Finsbury Park Mosque. He was arrested in England in 2004 for his alleged connection with the 1998 Yemen kidnappings that turned deadly (16 Western tourists were kidnapped in the Abyan region of Yemen; a shootout with the Yemeni military would leave four hostages and three kidnappers dead).
Hamza was reportedly found to have associations with the Taliban, al-Qaida, and the Aden-Abyan Islamic Army, a Yemen-based Islamist militant group. After extradition to the U.S. in 2012, Hamza was convicted in 2014 of all 11 terrorism-related charges and sentenced to life in prison.
Hamza is currently petitioning U.S. courts to send him back to England as his health deteriorates under the “inhuman and degrading” treatment at ADX. Hamza is a double-amputee and blind in one eye, allegedly after a chemical explosion in 1993, and legal filings state that the metal hooks he used as prostheses have been removed, his teeth are rotting, and he is kept in 24/7 confinement.
Mamdouh Mahmud Salim
- Known for: Cofounding Al-Qaida
- Sentence: Life without parole
In 1988, Mamdouh Mahmud Salim attended a meeting with Osama bin Laden and 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 and extradited to the U.S. for his role in the U.S. embassy bombings in Kenya and Tanzania that same year.
While imprisoned at a Manhattan federal jail in 2000, he sprayed hot sauce in the eyes of a guard, Louis Pepe, before stabbing him in the left eye with a makeshift shank—a sharpened comb—which penetrated his brain. Pepe’s left eye had to be surgically removed. His remaining eye only works at about 40 percent capacity, and the right side of his body is largely paralyzed due to the brain injury. It’s no surprise that Salim was deemed a danger to prison staff and moved to America’s most secure prison thereafter. Now, he is serving a life sentence for the stabbing.
Deceased Former ADX Florence Inmates
Ted John Kaczynski
- Known for: Being the “Unabomber”
- Sentence: Eight consecutive life terms
- Cause of Death: Suicide
Ted Kaczynski—born Theodore John Kaczynsk—grew up in a Chicago suburb and was by all accounts a brilliant student. He was admitted to Harvard University at the age of 16 and earned his doctorate in mathematics from the University of Michigan at age 25. At Harvard, he took part in a three-year ethically questionable psychological study that some speculate may have attributed to his later extremist beliefs and behavior.
In 1971, Kaczynski began his reclusive life in a secluded cabin in Montana where he penned his infamous manifesto, “Industrial Society and Its Future,” and began a 17-year effort to sabotage what he called the “industrial-technological system.” He mailed 16 homemade bombs that ultimately killed three people before he was discovered in 1996. Kaczynski was charged with three counts of homicide, 10 federal violations related to bombs, and was sentenced to eight consecutive life terms without parole.
Kaczynski was transferred from ADX to the Federal Medical Center in Butner, North Carolina, in December 2021 with late-stage rectal cancer, but the Federal Bureau of Prisons would not confirm the reason for his transfer due to “safety and security reasons.” The 81-year-old hanged himself with a shoelace on June 10, 2023.
Robert P. Hanssen
- Known for: Being a Soviet spy
- Sentence: 15 consecutive life terms
- Cause of Death: Colon cancer
Robert P. Hanssen was an FBI agent for 25 years from 1976 to 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. In his investigation of the case, chairman of the Commission for the Review of FBI Security Programs William H. Webster declared Hanssen’s treason “possibly the worst intelligence disaster in U.S. history.”
Hanssen died at ADX on June 5, 2023, from colon cancer. He was 79 years old and had been imprisoned in Colorado since 2002.
