"I won't tell in this letter what happened to me during the training sessions, what they did to me, or what they made me watch.

What I can say is that the human being is a beast. The training led to the systematic removal of all human functions of an individual and the destruction of their personality.

I witnessed terrible cruelties. I got to know hidden prisons, prisoners in a state of madness, including ex-military staff. My life became a hell."

Jorge Lubbert was only 22 years old when he wrote these words. He had fled from his native Chile to Germany months before in September 1978 and he was asking the German secretary of Amnesty International, Helmut Frenz, for help - the Chilean secret services had found him in Berlin and he was no longer safe.

What happened in the months before Lubbert's escape from Chile had traumatised him. Not long after reaching out to Frenz he found himself in the care of Jorge Barudy, a psychotherapist based in Leuven, Belgium. Barudy was part of a collective that helped refugees from Latin America who had been subjected to torture.

"Doctor Barudy believed that people who are traumatised have to vomit their trauma out in a way," explains Andres Lubbert, 32, Jorge's son. "They have to get it all out in order to move on."

Throughout his therapy sessions, Lubbert systematically told his story, which was recorded on audio tapes. Jorge's brother, Orlando - also in exile - typed the testimony out on 40 pages.

Jorge, who is now 61 years old, stuck around in Leuven. He married a Belgian woman and had two sons with her. Filmmaker Andres is the youngest.

The relationship between him and his father was strained. Jorge became a cameraman who often travelled to conflict zones, leaving his family behind for extended periods of time. He suffered from insomnia and, at times, struggled with addiction.

Andres never knew what had scarred his father. At age 19, he set out to investigate Jorge's history, travelling to Chile at least 20 times and documenting his findings in a series of films over the course of more than 10 years. Initially, his father wouldn't talk. Then, on a visit to Chile, Orlando gave a copy of Jorge's testimony to Andres.

"Up until then, I thought his experience was similar to that of other Chilean exiles, that he had been part of the resistance, a revolutionary, someone who was politically engaged and had to flee because of that," Andres told Al Jazeera.

"Reading [the testimony] was shocking, there are so many horrific things in there. It's a miracle he survived. I don't think many people would be able to live with a trauma like that."

Enlistment

From the testimony of Jorge Lubbert: "He presented me to a Mr Cano, a tall, burly guy. This person took me directly to the boss, called Jaime Letelier … 'We need you to work for us.' 'OK,' I said. 'Fine. As a draftsman, no problem.' He threatened me, using my father, my brother, who was abroad.

He told me that if I didn't sign, there would be no way out. That if I left then, I would not be safe anymore. 'Anything can happen to you.' I said no. No, I insisted, and he carried on in an aggressive, abrupt tone, insulting me.

He grabbed me by my jacket, shook me a bit and said, 'Sign!' They told me, 'You have all the skills we need and we will have them.' They told me not to resist, I had to sign. I had no way out and eventually, they made me give in, the pressure was too great. I signed the paper, the contents of which were covered up."

Augusto Pinochet came to power in Chile after he overthrew the incumbent Salvador Allende in a military coup on September 11, 1973. His 17-year rule was characterised by forceful repression of any opposition to his right-wing agenda. Around 3,200 people were executed or disappeared and about 28,000 people were tortured.

Many of the human rights violations that were committed during the dictatorship were perpetrated by the secret police, the National Intelligence Directorate (DINA) which in 1977 was replaced by the National Information Centre (CNI).

Jorge Lubbert had just started working at the Chilean Telephone Company when he was introduced to Jaime Letelier and made to sign a document that enlisted him in a CNI training designed to turn him into a state agent. It was the start of a four-month long horrific ordeal.

Learn more about the torture methods used against political prisoners in Chile during the Pinochet regime.

Kidnapped

From the testimony of Jorge Lubbert: "One Thursday, I arrived at my house, it was late. There was a vehicle, a new Chevy Nova, two guys quickly got out, grabbed me violently and tried to get me into the car. "F**k," I thought. They were abducting me.

I screamed, I kicked, I kicked furiously. They got me into the vehicle. I didn't understand what was happening, then something unusual occurred. Behind the wheel was a person I knew, he was the brother of a friend of mine. He's called Jose Pavez, and I knew him as a tank lieutenant stationed in Antofagasta."

"I have Jose Pavez's military record here," Andres tells his father. It's December 2015 and the two are standing in the hallway of a building in Barrio Olimpico, Santiago de Chile, the neighbourhood where Jose Pavez lived back in the 1970s.

"Where did you get it from?" Jorge responds. He reaches out to the blue folder and nervously pulls it from Andres's hands. "If he finds out we're investigating him and his accomplices from the secret service… I'm sure he still has contacts, he can find me in five minutes. Me, you, my brother Orlando - all of us," Jorge says.

Throughout his four months of training by the CNI, Jorge Lubbert would routinely get abducted, blindfolded and taken to secret locations. "He lived in constant paranoia that they could take him at any moment," Andres tells Al Jazeera.

Jorge's fear persisted in Belgium, and even today. Andres remembers how his father would hide in the toilet when someone knocked on the door. He still doesn't open letters.

Like most of the people Jorge identifies in his testimony, Jose Pavez Ahumada was never charged with violating human rights during Chile's military dictatorship. Only one of the men mentioned by Jorge, Rosauro Martinez Labbe, is currently under investigation for his alleged responsibility in the killing of a group of leftist activists in 1981.

More than 27 years after Pinochet's rule came to an end on March 11, 1990, the process of bringing human rights abusers to justice is still ongoing. Between 1998 and 2015, 344 former agents of the state were sentenced for human rights violations, with another 1,048 under investigation as of December 2015. On June 2, 2017, 106 former DINA agents received prison sentences in the biggest mass sentence to date for human rights abuses committed under Pinochet.

Find out more about ex-Chile spy chief, Manuel Contreras, reviled for his role in kidnapping and killing thousands during General Pinochet's rule, who died while serving 500-year sentence

Tortured

From the testimony of Jorge Lubbert: "A very tall guy came, a commando with a rubber apron and rubber gloves. He made us enter a large room with tiles and a rather unpleasant chemical odour.

There were three corpses. Without warning, the guy with the scalpel took hold of the corpse's testicles and cut them off. My stomach started churning, I went very pale. The guy approached me and gave me a piece. He put the jaw into my hands and I just fainted.

When he woke me up he said I needed to get used to being around death. You have to know about these things. He furiously grabbed a piece of flesh and rubbed it in my face. He went wild, he was mad at me."

"What did this have to do with me?" Jorge Lubbert asks himself. He is standing in front of what is now an amphitheatre in the Legal Medical Institute of Santiago de Chile. Nowadays, medical students study corpses here. Back in the late 1970s, the venue was controlled by the CNI.

"It was to dehumanise you, to rid you of all emotion regarding the human body. So you saw no difference between dead and alive," Jorge continues. "When you get used to seeing a corpse, it's like seeing an animal. This is actually very much like a slaughter house."

It is still unclear why the CNI singled Jorge out for their experiment to turn a 21-year-old youth into an instrument of the secret police - someone who could kill for them.

"He had technical skills, was easy to like and had a leftist group of friends without being politically engaged himself," says Andres. "But we'll never know for sure why he was chosen - the people who participated are now part of silence pacts." As far as Andres knows, his father's case is the only one of its kind that has been recorded.

Despite the unspeakable cruelties which have come to light since the end of the military dictatorship, like the ones inflicted on Jorge Lubbert, the Pinochet era is still a cause of division in Chilean society.

A study conducted by CeRC-Mori in July 2015 found that 15 percent of Chileans still view Pinochet as "one of the best rulers Chile has had", while slightly over a fifth of those polled said the military coup was justified.

"There are two levels of support for Pinochet," says Javier Rebolledo, a journalist who specialises in investigating human rights violations perpetrated by the military government. "The people who would jump up and shout for Pinochet, give thanks to their general - there are very few of them left, at least those who dare to show themselves that way," he tells Al Jazeera.

"But there's another group of people who are still Pinochetistas, but in a hidden way. They know it's politically incorrect to support Pinochet but they do, in silence. For them, there is almost a separation between what he did for the country economically and in terms of human rights violations."

Read this related article to find out more about how Pinochet-era crimes still haunt Chile

Escape

From the testimony of Jorge Lubbert: "I realised I was slowly being drawn deeper into it. Sometimes, I felt like one of them. I could not accept that. I couldn't imagine working with someone who I'd see kill another person.

I felt guilty. I felt like an accomplice for being there. What saved me is that I never lost touch with my family."

On September 2, 1978, Jorge Lubbert escaped to Germany with the help of his father, before the CNI's training was completed.

"What saved my father was his upbringing. He was raised with a lot of love. He was his mother's favourite. He could never betray his family and be transformed in what the secret police wanted him to become," says Andres.

Throughout Andres's investigation into his father's past, talking about what had happened was difficult for Jorge - and he has now reverted to not broaching the topic at all. "He recently told me this is now over for him," Andres says.

Still, he hopes that his most recent film about his father's story, The Colour of the Chameleon, will encourage a transgenerational debate in Chilean society.

"What I've learned is that when traumas are ignored, they are passed on from generation to generation," he says. "Parents try to protect their sons and daughters from trauma by not discussing it, but that only makes the problem bigger and deeper. The only way to heal a society is by starting a dialogue."

Watch more from Andres and Jorge Lubbert's journey into Chile's dark past in The Colour of the Chameleon on Witness.