“We’ve seen death, we’ve seen a lot of things, but we’ve never seen anything like this,” says Cyprus’s veteran fire chief, Marcos Trangolas. “So far, we’ve found two bodies in suitcases in this lake, both badly decomposed. It’s hard for the human mind to take in.”

Three weeks on, the gruesome acts of a self-confessed serial killer continue to send shockwaves through this island nation.

As the man overseeing the special disaster unit searching for victims in two manmade lakes barely 20 miles from the Cypriot capital, Trangolas is at the sharp end of revelations that in the space of days have seen the justice minister resign, the police chief replaced and protest vigils held. “Like everyone we are shocked,” he tells the Guardian. “We’re asking questions.”

Cyprus’s fire chief, Marcos Trangolas, speaks at the Red Lake near the village of Mitsero. Photograph: Iakovos Hatzistavrou/AFP/Getty Images

No single event in recent years has pierced the tranquil peace of Cyprus as much as the murder of seven foreigners – five women, two girls – whose disappearances initially went ignored. Had it not been for the chance discovery of a body in a rain-flooded mineshaft, police may never have launched the investigation that led to the arrest of a Greek Cypriot army captain, who – authorities maintain – has admitted to preying on women in low-paid household jobs in a 10-page handwritten confession.

Guided by that testimony, investigators have since recovered five bodies, including that of Mary Rose Tiburcio, a 38-year-old Filipino discovered in the abandoned mine on 14 April by bikers out riding the dirt roads of rural Cyprus.

Search efforts are focused on the lakes where the 35-year-old National Guard officer, Nikos Metaxas, has admitted dumping four of his victims.

Several victims are thought to have been dumped in Cypriot lakes. Photograph: Katia Christodoulou/EPA

Last weekend, specialist divers, deploying a robotic camera, retrieved a suitcase weighed down by a cement block, containing the remains of a human body in the muddy waters of a red lake, part of a now-defunct copper pyrite mine.

It was the second such find in a week. Horrified Cypriots are demanding answers.

Charges of police ineptitude have been widespread, with “institutionalised racism” cited as the cause of delayed attempts to catch the mass murderer.

Since 1974, when the island became the scene of violent inter-ethnic strife culminating in a coup prompting Turkey to invade, Cypriots have taken comfort in a lifestyle that is both remarkably laid-back and free of hardened crime.

The scale of the crimes and alleged cynicism of the suspect has increasingly left people reeling, and, say campaigners, confronting uncomfortable truths about the way foreign workers are treated on a tourism-dependent island where domestic household workers are invariably from the Indian subcontinent and south-east Asia.

Women light candles in memory of the victims. Photograph: Katia Christodoulou/EPA

The women, four of whom were Filipino, had moved to the Mediterranean country as household staff, with the first victim, Livia Florentina Bunea, a 36-year-old Romanian thought to have been killed, with her eight-year-old daughter Elena, in September 2016.

When alerted to Tiburcio’s disappearance, one police officer reacted saying he was “too old to concern himself with Filipino women”, according to the island’s Domestic Workers’ Association.

As the extent of the killing spree came to light, the realisation that a serial killer has been in their midst has elicited dismay, but also sympathy for the victims, who had been disregarded by most.

“It’s very sad that it has taken such tragedy but there has definitely been a shift in the way the media and society now see migrant domestic workers,” says Doros Polycarpou, who heads Kisa, a refugee and migrant support group. “There’s no question that these people work in conditions of extreme exploitation. They do not enjoy the same rights as Cypriots.”

Police apathy has been the target of protesters as they took to the streets of Nicosia again this weekend. Many are asking how the suspect could have acted with impunity for almost three years.

As the island’s new police chief, Kypros Michaelides, assumed his post this week, he acknowledged the public outcry and apologised to the families of the victims. He conceded security forces “had failed to protect innocent and defenceless souls who found death in such a tragic and hideous manner”.

Filipino women take part in a memorial for the victims at the mineshaft where two female bodies were found. Photograph: Petros Karadjias/AP

Evidence gathered since the revelations has revealed a pattern of police failing to follow up cases. Officers often claimed victims had absconded to the war-divided island’s Turkish-run north, which lies outside the remit of the internationally recognised Greek south.

“I will do whatever is humanly possible … to reclaim lost ground and the trust of society in the police and its members,” Michaelides vowed at a sombre ceremony attended by President Nicos Anastasiades.

Police believe Metaxas lured the women through online dating sites and informal community groups supporting domestic migrant workers. Although he has not been formally charged, his remand in custody has been repeatedly extended as police process a “deluge of information” about his activities and build up an airtight case against him.

The Cypriot police chief, Kypros Michaelides, speaks during the search for bodies of victims. Photograph: Iakovos Hatzistavrou/AFP/Getty Images

A five-strong team of Scotland Yard experts specialising in such crimes have also flown to Cyprus to help crack what is being treated as the country’s first serial killing.

The British investigators, who are participating in the interrogation of the officer, have not ruled out other murders.

The EU’s most easterly member state, Cyprus has about 30,000 registered domestic workers, including a sizeable population of Filipino workers employed by its middle-class. The housekeepers earn about €400 a month – well below the minimum wage.

Of the five bodies recovered to date, three were found naked, and bound and wrapped in sheets. Authorities say they include two Filipinas retrieved from the mineshaft where the tragedy first started to unravel and a suspected Nepalese woman discovered at an army firing range after investigators were led to the site.

Police think the two suitcases retrieved so far from the red lake contain the remains of Bunea and her daughter. A third suitcase believed to contain the body of Maricar Valtez Arquiola, a 31-year-old Filipino woman, has yet to be found. Arquiola went missing in December 2017.

A boat equipped with a sonar system crosses the Red Lake in an effort to find evidence. Photograph: Iakovos Hatzistavrou/AFP/Getty Images

Trangolas, the fire chief, said the search was still on for another child, six-year-old Sierra Graze Seucalliuc, who went missing with her mother, Mary Rose, in May last year. Her body is thought to be in a second lake closer to the mines.

Headway has been hampered by poor visibility in the lakes’ waters, the by-product of years of mining in the area, despite divers in recent days using specialist sonar equipment.

“We’re talking about visibility of less than five to 10 centimetres because the water is so muddy, so full of chemicals and so polluted,” he says.

Trangolas spends “every waking moment” overseeing the operation at the lakes. “Saturdays, Sundays, holidays and feast days, we’re here and like everyone else we’re shocked too,” he says.

“We’re professionals but there have been tears; emotions have run high when the suitcases come to the surface and we have seen what we have seen.”