NAIROBI, Kenya — In Kenya, where the police have long been known to harbor death squads, evidence mounts that many ordinary cops on the beat have turned into killers — doling out death to terror suspects, civilians, even children.

And shakedown victims like three cable guys who, on one hot day on a dusty street corner of a sprawling Nairobi slum, pleaded with police for a break.

They earned their living installing pirated cable, giving locals an illegal discount on Latin American soap operas and British soccer. But earlier that day, two plainclothes officers had confiscated their equipment, demanding a bribe for its return.

The police wanted 50,000 Kenyan shillings, roughly $550. When the cable guys said they only had $230, the officers threatened them, said Mohammed Gulow, the oldest of the three.

"He told us we are going to see fire and returned to the car," said Gulow, 34. "We soon saw fire."

The officer rolled down his window, aimed a pistol and shot twice, according to Gulow and his buddy, Adan Hussein. The first bullet hit Aliyow Alinoor and sent him reeling through a shanty door. The second bullet caught Hussein in the arm, shattering the bone.

Alinoor, 21, was pronounced dead at a nearby hospital. Hussein, 33, lost the use of his hand.

The May 13 shooting in Mukuru slum, recounted to The Associated Press by Gulow and Hussein, is one of hundreds of similar cases, according to other eyewitness accounts and interviews with human rights workers. Underpaid, caught up in a brutal war with terrorists, too many police have become outlaws themselves. And the evidence suggests that the killers are rarely punished.

Concerns about impunity were also raised when the International Criminal Court's chief prosecutor in The Hague on Friday dropped all "crimes against humanity" charges against Kenya's president for lack of evidence. That case was linked to violence after the 2007 elections.

Police said the shooting in Mukuru is being investigated. Gulow says no action has yet been taken against the officers.

Dr. Eric Thuo, a forensic specialist at the Independent Medico-Legal Unit, a Kenyan human rights organization, studied gunshot-related deaths in six major urban areas between 2009 and 2014. By examining post-mortem records, he found 1,873 gun deaths. Police were involved in nearly two-thirds of them, many of them suspected assassinations.

"Illegal killings are the norm rather than the exception," Thuo wrote in his report.

Thuo's findings, which he says are conservative, contradict Kenya's official statistics. Thuo was told by the Independent Police Oversight Authority that only 120 people were fatally shot by police between September 2012 and February 2014.

But Thuo's post-mortem reports indicated that nearly twice that many died from police fire in six cities alone — Nairobi, Mombasa, Eldoret, Kisumu, Kakamega and Nyeri.

Kenyan police spokeswoman Zipporah Mboroki declined to comment about the allegations of police executions. The Independent Police Oversight Authority would not comment on how many of the police killings were suspected of being extrajudicial assassinations.

But some officers acknowledged the killings, and even their own participation — though they would not be identified, for fear of reprisals. Three senior officers who spoke to AP confirmed that such killings were common. Bosses are well aware of what's going on, the officers said, adding that, in some cases, the orders to kill suspects come from the bosses themselves.

The constant killings are spreading fear, breeding corruption and have the potential to inflame Kenya's terrorism problem.

"The broader picture here is one of utter impunity," said Leslie Lefkow, deputy director of Human Rights Watch's Africa Division. "My fear is that the pattern of extrajudicial killings will only worsen."

Some of the deaths, like Alinoor's, come from alleged shakedowns gone wrong. Others are committed to make a point: One officer said he had had taken part in a killing in the capital.

"I took part in an extrajudicial killing at the time there was pressure to reduce muggings downtown and we needed to send a message," the officer said, without giving details on who was killed.

Others come from increased police vigilance in poor neighborhoods — like the Somali enclave of Eastleigh, just outside Nairobi — in an attempt to fight terror, an effort that has been financed by the United States and other Western nations.

The Islamic militant group al-Shabab has been fighting for years to establish Islamic rule in neighboring Somalia. When Kenya sent in troops, the group, which is linked to al-Qaida, retaliated with terrorist attacks. It claimed responsibility for the Westgate shopping mall attack in Nairobi last year that left 67 dead, along with two recent massacres of non-Muslim civilians.

Observers say Kenya's bid to crush al-Shabab is often used as cover for a wide variety of abuses.

The bodies of Yusuf Mohamed and four of his friends — Mohamed Kaburu, Kevin Kahuri, Simon Kingori and Martha Wairimu — were discovered deep in a forest near the central Kenyan city of Nyeri on April 17. The men had been shot in the head. Wairimu's corpse was hanging from a nearby tree.

The last time Mohamed and his friends were seen alive, his family said, they were in police custody.

The five friends, aged between 20 and 25, had been watching a soccer match at a local pub. After the match, police arrested the four men and drove them toward the Nyeri police station. Wairimu was not arrested, but she followed them in a taxi with cash to bail them out.

Local reporters quoted unidentified police sources as saying the group had traveled to Somalia to train with al-Shabab, an allegation their families deny.

"At the time they are supposed to have been training with the al-Shabab in Somalia, they were in the country shuttling between court hearings and school," said Saida Mohammed Kaburu, Mohamed Kaburu's mother.

She believes the real reason the men were killed was for opposing a local gang with allies in the police.

"They were totally innocent," she said.

Advocates worry that police brutality will serve only to drive Kenyan youth into the arms of al-Shabab.

"There's no question that these kinds of abuses against communities can contribute to radicalizing youth," said Lefkow.

Human rights activists have blamed Kenya's Anti-Terrorism Police Unit, or ATPU, for some of the worst abuses. Suspects have been shot dead in public places, abducted from vehicles and courtrooms, beaten during arrest and denied contact with their families or access to lawyers, according to a Human Rights Watch report released in August.

The research — conducted between November 2013 and June of this year — documents at least 10 cases of killings and 10 cases of disappearances linked to the ATPU. The rights group also documented another 11 cases of mistreatment and harassment of terrorism suspects.

"The last time these people were seen was in the hands of the government agents," said Francis Auma, an officer with the Mombasa-based Muslims for Human Rights. "The government's reluctance to investigate these cases also makes it complicit."

Masoud Mwinyi, a police spokesman, said those allegations are not true.

The West shares some responsibility for the emboldened ATPU. Following the 1998 U.S. Embassy bombing in Nairobi and the Sept. 11 attacks, Western governments spent millions of dollars to help Kenya control the terror threat. The U.S. alone provides an average of $8 million a year to Kenya's security forces, including police units.

The U.S. State Department on Friday urged the Kenyan government to investigate all of the reported claims. Spokeswoman Marie Harf said all the trainees and units that the U.S. works with have been screened thoroughly as required by U.S. law. The training, she added, is intended to increase the professionalism of the forces and includes support "to improve accountability and transparency in the police services."

Britain's Foreign Office says it gives training and "capacity building support" to the ATPU, but refuses to put a figure on the assistance. In a statement, it said the money was "designed to build the capacity of the Kenyan authorities to deliver peace and security in line with domestic and international law."

The foreign money has not made its way into higher salaries for police. Officers make an average of $200 to $300 a month, something Washington-based East Africa scholar Samuel Aronson said was "not a sustainable salary, even by Kenyan standards."

That means officers often look to supplement their income, giving Kenya's police the reputation of being the most corrupt institution in an already corrupt country, according to Berlin-based Transparency International.

After a spate of violence in 2008, officials promised to reform the police service. But attempts to improve the working conditions of police officers has only meant more money for corrupt Kenyan elites, according to anti-corruption campaigner John Githongo, while reform work has stalled amid bureaucratic turf wars.

Meanwhile, the hunt for cash means some police officers pair extrajudicial killing with theft. Human rights groups have documented cases where suspects have been allegedly extorted by police and then killed.

That's what appears to have happened on May 5, when four men who identified themselves as police dragged Mohamed Abdi Mohamed from his shop in Eastleigh, according to the shopkeeper's cousin, Mohamed Shine.

The men said Mohamed was being taken to Pangani police station. But when his relatives went there to look for him, they were told he had not been booked there, said Shine, who spoke to the AP with other family members.

The family searched for Mohamed through the night. In the morning, they noticed that 50,000 Kenyan shillings had been withdrawn from his Barclays bank account, Shine said.

Fearing the worst, the family called the morgue repeatedly over the next three weeks. They heard nothing until a relative paid off a mortuary attendant.

The attendant revealed that police brought Mohamed's body to the morgue on May 25 along with the remains of two other Muslim men. The three were found floating near the Masinga Dam, some 90 miles (145 kilometers) northeast of Nairobi, Shine said. The police had ordered the staff not to say anything about the bodies, the attendant said.

The atmosphere of intimidation reaches from the morgue all the way to the highest levels of the Kenyan government.

Last year, just before the vetting process for security contracts aimed at overhauling Kenya's police, a package was left outside the office of Johnston Kavuludi, the chairman of the commission in charge of the reforms.

Inside were a human head, two hands and a note saying: "Kavuludi, you are next."

Still, hopes persist. When the country's top cop, Inspector General David Kimaiyo, resigned on Tuesday, only hours after al-Shabab's second mass slaughter, critics cheered his departure and urged reforms of the police and corrupt government institutions.

And occasionally, police are called to account for the deaths.

Two officers recently were charged with the killing of 14-year-old Kwekwe Mwandaza, whose ramshackle house in a Kenyan coastal village was raided by eight police officers on August 22. The officers shot her in the head and tried to dump her body in the forest, according to human rights lawyer Harun Ndubi.

But her case was an exception. Few families get justice. Some never even get answers.

Abdifatah Odowa Adan, a 30-year-old bus company manager, disappeared on May 5. He had been stopped by five men, one of whom flashed a police badge. When Adan's relatives traced the taxi they'd taken, the driver identified the captors as undercover officers, according to his sworn statement.

Mohammed Korane Abdi, Adan's relative and an assistant at the bus company, said it was the first time Adan, a father of three with two wives, had a brush with the law. He said they had obtained court orders asking the police to explain the reasons for detaining Adan and why he should not be released, but the police denied having arrested him.

"The government has the right to secure the safety of the nation. We are not saying Abdifatah is not at fault," said Abdi. "We, as his brothers, have the right to know if he is alive or dead. If he is alive, let him be charged in court, but at least we will know that he is alive. If he is dead, let his people bury him.

"The uncertainty is too much to bear."