He's been under witness protection and remains in hiding. He has an outstanding case against his former boss and the Philippines' current president, Rodrigo Duterte, who is under investigation by the country's Human Rights Commission.

Warrant pending

The government also has an arrest warrant out for him -- for not showing up in court on charges of possession of illegal firearms -- and has also charged him with a kidnapping in 2002.

Even though he's claimed to have killed dozens of people, they wouldn't dare charge him with murder, he says, as that would be an admission of wrongdoing on the part of the Duterte administration.

After decades in the employ of the Davao City government -- as an assassin, he says -- Matobato has now turned against his former paymaster.

In testimony to the Philippines Senate in September, Matobato said he was part of the Davao Death Squad (DDS), which he alleges was run on the orders of Duterte.

"Our work was to kill criminals like drug pushers, rapists, snatchers," he testified at the time. "Those were the people we killed every day."

CNN has not independently confirmed Matobato's allegations.

Secrecy at all costs

We are met on the road by his handlers some distance away from the compound, a necessary caution. He's in danger of being killed himself these days, as a key witness to -- and actor in -- what he says was a series of unspeakable crimes from 1988 to 2013.

During that time he says he was part of the DDS, an allegedly state-sanctioned group of murderers who, alongside him, he says, killed as many as 1,400 people in the southern city under then-Mayor Duterte.

At first, he thought he was doing something just: ridding his town of bad people. But over the course of his career as a hit man he came to realize that he wasn't on the side of justice. In 2010, he says, he was ordered to kidnap and kill bodyguards and associates of one of Duterte's political rivals. Of the four bodies they dumped in the sea, two resurfaced.

It was one of the incidents that chipped away at an already dented conscience, leading to his recent claim that he was a killer for Duterte.

Another time, he recalls, three young women suspected of dealing shabu -- the local name for methamphetamine -- were bound, beaten and raped by DDS members, then killed.

Marked for death

His former colleagues -- who numbered 300 at the height of the group's existence -- would kill him if they find him, he says matter-of-factly.

"I don't care anymore if they want to kill," he says. "What I want to do now is to tell the truth and not to lie anymore."

He wants to atone for the wrongs of his life in the DDS, and as a fervent Catholic, he says that he believes his God will forgive him, such is his genuine remorse.

He wears a sizable wooden cross outside his tight, white polo shirt and he says he is ready to face the judgment -- in this life or the next -- that his past demands.

For his part, Duterte has dismissed the 57-year-old as a liar and said he doesn't remember him, but Matobato tells CNN that he murdered around 50 people in a 24-year career as a hit man as part of the DDS; criminals and political rivals of the then-mayor in his hometown, the largest city in Mindanao in the country's restive south.

Duterte's press secretary, Martin Andanar, says that the DDS is nothing but a myth.

"Everybody talks about the death squad," he tells CNN.

"There is the Philippines National Police. That's the authority. The death squad, the Davao Death Squad that people are talking about -- this is all legend. It's a legend. There is no death squad. There is the police and there is (the) AFP (Armed Forces of the Philippines)."

Kidnap, murder

Matobato remembers it differently. Most often the DDS would kidnap their victims, he tells CNN, take them to a quiet part of town -- like a quarry -- and kill them before dismembering the bodies, dousing them in oil to keep them from smelling as they decomposed and burying them, or dumping them at sea, Matobato says.

For those disposed of at sea, they'd hack open their victims' chest cavities, to ensure that the corpses sank, he recalls.

He says that the orders mostly came from a ranking police officer, but on occasion, he says, Duterte himself would order the killings.

In 1993, after the bombing of the city's cathedral, Matobato says, Duterte personally told him and other DDS members, in the mayoral office, to go to a mosque and kill Muslims in reprisal for the terror attack.

On a different occasion, he alleges Duterte shot and killed a National Bureau of Investigation agent after a traffic altercation led to a shootout. The then-mayor emptied two full magazines of bullets into the agent, he said.

Parallels with war on drugs

In the six months since Duterte took office as president, lurid images of extrajudicial killings crop up every morning in Filipino newspapers -- vigilante justice, or police operations known as "buy busts" that invariably end in the death of the alleged dealer.

Matobato says they bear the hallmarks of those perpetrated by the DDS -- faces bound in electrical tape, crude cardboard signs around the victims' necks, proclaiming their alleged crimes.

He says DDS operatives would carry an extra, cheap pistol with them to dump near the bodies, claiming a shootout took place.

Almost all the police "buy bust" operations end with similar reports, and the morning papers' crime scene photos often feature handguns next to sprawled, bloodied bodies. Matobato says he's seen former DDS colleagues in Manila.

"Members of the DDS are already ... in Manila," he says. "The policemen in Davao City are capable of killing... They don't have a soul, these members from Davao."

Killer hired for a pittance

Officially a security official under the employ of City Hall, Matobato says that he and the other DDS members were rarely called upon to do their official duties -- "such as securing the port" -- but mostly were just used to carry out extrajudicial killings. He, and the others, were paid P5000 ($100) a month for their work, he told CNN.

Others had tried to get out, he says, but at least one former member was run over shortly after trying to escape the group's clutches.

He says that he begged to get away from the butchery, but in 2014 the kidnap and murder of a businessman was pinned on him. He insists he had nothing to do with it.

"They tortured me and kept me for a week. Every night they will torture me. My relatives helped me and I got out."

He told his wife of his grisly past and together with their two kids they fled the city and, later, went into the Human Rights Commission's witness protection program. Even though the HRC is an independent government agency, Matobato left its program when Duterte became president.

And earlier this year, he took the witness stand to speak out about the group's bloody work.

But presidential spokesman Andanar says that the testimony of the self-declared former killer, who only has a first-grade education, is "very inconsistent" and not to be trusted.

"If you go through the transcript of the Senate you will see for yourself that Matobato is lying through his teeth," he says.

After he first testified at the Senate inquiry into alleged extrajudicial killings, Matobato was placed under the protection of a private citizen.

And now, a life interrupted; a series of furtive moves around the countryside, never knowing if he will suffer the same violent death he says he meted out so many times.

He wants his testimony to bring down the President, a man he says is no more than a bloody butcher who has carried over his brutal methods from Davao onto the national stage.

"(Duterte) should pay for all his sins. If the death penalty (is reinstated), I wish he will be the first to be hanged.

"Then I will follow. Yes, I am willing to follow."