Alex Friedmann was rearrested on Tuesday after authorities discovered his burglary charge was allegedly connected to a plan for a mass jail break from a Nashville prison

A longtime prison reform advocate and former convict has been arrested for his alleged 'evil plan' to start a mass jail break by hiding loaded guns and 'escape devices' such as bolt cutters in an under-construction Tennessee prison.

Alex Friedmann, 50, an ex-prisoner turned crusader against private prisons, was charged in January with attempted burglary, accused with gaining access to the new jail on several days in December by dressing as a construction worker and stealing keys.

As the investigation continued, police discovered Friedmann's 'burglary' was all part of a further jail break plot in which he allegedly hid a weapons stockpile in the Nashville jail.

He was accompanied by three other men police are still trying to identify.

Authorities announced on Wednesday that Friedmann is now charged with vandalism of $250,000 or more.

'It was discovered that Mr. Friedmann, over many months, had developed and implemented an extremely deliberate and, in my opinion, evil plan,' Nashville Sheriff Daron Hall said during a Wednesday news conference announcing Friedmann´s re-arrest on upgraded charges.

'What disturbed me most is not that this was about an escape, it was also about loss of life.'

Hall said he believes Friedmann was the ringleader in designing the massive jail break that would endanger 'every inmate, every visitor and our entire community'.

'Virtually everything I'm telling you is on video,' Hall said, noting that investigators have poured through hundreds of hours of video to identify the areas of the building that were compromised.

Alex Friedmann spent 10 years in jail for intent to murder and armed robbery but was alleged to have changed his life, becoming an advocate for prisoner rights and a critic of private jails

The new detention center in Downtown Nashville where Friedmann and three other suspects allegedly stole a key and dressed as construction workers so they could hide weapons

Friedmann was first caught and arrested on January 4 after entering the building for what is believed to be the fifth time. He was dressed as a construction worker at the time.

He was charged with burglary, possession of burglary tools and evidence tampering after he was found with a cooler containing bolt cutters, a key chit (used as a security measure to identify keys), and a schematic document of the building.

When caught, he allegedly tried to destroy the document by ripping it up and chewing it.

Friedmann refused to answer questions from police and was initially charged with burglary until police watched further surveillance footage and discovered his alleged jail break plan.

Further searches also revealed three loaded guns and further escape tools hidden in the detention center.

One of the men Metro Nashville police is attempting to identify as Friedmann's accomplice

These two men are suspected to be accomplices of Friedmann and were caught on surveillance footage as they allegedly dressed as construction workers to enter the jail

He is believed to have entered the facility on several occasions in December, including on December 26 when he was accompanied by a man wearing a face mask and construction worker clothes.

Friedmann interacted with two other men during visits, who police are also trying to identify.

The Metro Nashville Police Department tweeted a photo of the other three suspects and called on the public to help identify them.

On one of the days, Friedmann allegedly stole keys from the control room. The loss of keys and the discovery of the key chit is believed to have compromised the safety of the whole jail and will require all 2,000 locks to be refitted before it can safely open.

Hall added that the case was particularly shocking because Friedmann is known in Tennessee as an advocate for prisoner rights.

Alex Friedmann was sentenced to ten years for intent to murder in 1991, mugshots pictured here, but was said to have turned his life around and become an advocate for prison reform

Alex Friedman being booked during his arrest for burglary in January. Police later discovered that this may have been part of a larger jail break plot in which weapons were hidden

'Mr. Friedmann served time and has spent a long time advocating for safe jails and prisons,' Hall said

He was believed to have turned his life around after spending a decade in jail, sentenced to ten years behind bars in 1991 for assault with intent to murder and armed robbery.

Up until his arrest for burglary in January, Friedmann has been the associate director for a prison watch group called Human Rights Defense Center (HRDC), under which he was a longtime editor at Prison Legal News.

Friedmann resigned as editor after his earlier arrest, executive director Paul Wright said in a telephone interview.

He was also a consultant for Senator Bernie Sanders' office when they were compiling a report for a new bill to ban private prisons in 2015.

Friedmann's attorney, Ben Raybin, issued a statement on Wednesday.

'I am currently unable to comment on any of the factual allegations,' Raybin said.

'Mr. Friedmann is presumed innocent and will respond through the appropriate legal processes.'

Friedmann is being held in Riverbend Maximum Security Institution and is due to appear in court in April. His bond has been set at $2.5million

A GoFundMe has been established for Friedmann's legal defense, describing him as 'a national expert on private prisons and other criminal justice issue'.

The page claims that 'his intentions were consistent with his history of advocacy and activism' and that 'his arrest was totally unexpected and completely unlike him'.

It alleges that there is 'obviously much more to this story, but he can’t tell it or explain his actions'.

Construction photos of the new Nashville prison where Friedmann allegedly hid weapons. The new prison was due to open in April but is now been delayed as they search for weapons

Riverbend Maximum Security Prison where Alex Friedmann is being held

Hall, who currently serves as president of the National Sheriff´s Association, said no one there has ever seen anything like this before.

'It will forever change how correctional facilities are built,' he said.

The Nashville Downtown Detention Center was scheduled to open in April but its construction has now been delayed as authorities sweep the building for further hidden ammunition.

'I'm not confident we've found everything,' Hall said.

'We're not going to work here until we're comfortable.'