Serial killer Rex Heuermann is finally going to hell.

It comes in the form of one of New York state’s oldest prisons, a bleak facility isolated in the frigid Adirondack Mountains near the Canadian border.

Know as “Little Siberia,” the infamous Clinton Correctional Facility in Dannemora, NY, opened in 1845 has warehoused some of the nation’s most evil killers.

It was also the scene of a dramatic jailbreak in 2015 that was immortalized on film.

The former Manhattan architect, who plead guilty to the murders of eight women, will join fellow Long Island serial killer Joel Rifkin and New York Zodiac killer Heriberto Seda behind its 60-foot-high, 7-foot-thick concrete walls “as the classification and assessment process continues,” state prison spokesman Thomas Mailey said.

Clinton is the state’s largest maximum-security lock-up, and many of its ancient cells measure roughly 6 by 8 feet, containing only a steel-framed bed, toilet, sink, and small writing surface.

At Dannemora, 62-year-old Heuermann will find himself alongside the worst serial killers in history, such as Rifkin, 67, who is serving a 203-year sentencefor killing 17 prostitutes. 

He’ll also be joining Seda, who is serving 232 years for killing three people and wounding five in the early 1990s after becoming obsessed with California’s infamous Zodiac Killer.

Seda, who shot and stabbed his victims, was caught before he could kill 12 people representing all the Zodiac signs.

A third serial killer, Altemio Sanchez, died in 2023 while serving his sentence of 75 years to life at the prison.

Known as the “bike path rapist,” he killed three women between 1990 to 2007 in western New York.

Other noted killers at Dannemora include former NYPD officer Michael Valva, 47, who was convicted in teh freezing death of his autistic 8-year-old son in 2020.

Convicted killers David Sweat and Richard Matt carried out an elaborate jailbreak on June 6, 2015, drawing international attention.

Two prison employees — including Joyce Mitchell, a sewing instructor dubbed the “Shawshank” because she was reportedly sleeping with both killers — helped them smuggle tools into the facility. The duo cut through their steel cell walls, then navigated a maze of wiring corridors, and cut through a steam pipe to come out through a manhole outside the walls.

A three-week manhunt ensued covering 75 heavily-wooded square miles.

Matt was shot and killed by law enforcement officers and Sweat was shot and captured alive two days later.

The 46-year-old was sent back to the maximum security prison after he was caught and remains there today.

The breakout led to the 2018 true-crime miniseries Escape at Dannemora directed by Ben Stiller.

Additional reporting by Sonya Gugliara