Arnel Oares, Jeremias Pereda and Jerwin Cruz are the first police officers to be convicted of crimes committed in the drug war, which has claimed thousands of lives, mostly those of suspected low-level drug dealers and users.
Sentenced by a judge in Caloocan city, north of the capital, the three were also ordered to pay damages of 345,000 pesos ($6,586), according to CNN affiliate CNN Philippines.
The officers were found not guilty of planting drugs and a firearm on Delos Santos.
The convicted officers denied any wrongdoing, saying Delos Santos pulled a gun, forcing them to open fire.
However, security footage from the scene appeared to contradict their claims, showing the teen being dragged across a basketball court by officers shortly before he was shot three times. He was shot twice in the head and once in the chest, according to autopsy reports.
The government estimates 5,000 people have been killed in police drug raids. Many more are estimated to have been the victims of vigilante violence.
Senior opposition figures claim tens of thousands of people have been murdered in the name of Duterte’s draconian drug policy.
Sentencing ‘triumph of justice’
Rights groups welcomed the verdict and sentences handed to the three police officers on Thursday.
“This is a triumph of justice and accountability and a warning to members of the Philippine National Police to respect due process and the rights of civilians as they do their job,” Human Rights Watch’s Asia director Brad Adams said in a statement.
However, he also warned that the organization remains “wary because Duterte has promised to pardon police officers convicted in the ‘drug war’ killings. There is reason to suspect that he will keep that promise.”
The Delos Santos case sparked outrage including protests and a parliamentary inquiry. His death was seen as a potential tipping point for a country weary of the bloody crackdown.
Duterte has a long history of tolerating, even encouraging, police officers to kill drug suspects, but he said the Caloocan police who slayed Delos Santos had gone too far.
“You are not allowed to kill a person who is kneeling down, begging for his life. That is murder,” Duterte said. “Let us be clear on this.”
He said that after seeing the footage he demanded that the killers be arrested.
“(The media was unaware), but right after it happened, I called Bato. ‘Arrest the guys and place them in jail to wait for inquest.’ (Push through with the case) if it’s murder,” he said, referring to Ronald Dela Rosa, the then head of the Philippines police, by his nickname.
Delos Santos’ father, Saldy, said that Duterte’s intervention had allowed the couple to find peace.
Duterte was elected to office in June 2016, campaigning largely on a pledge to eliminate the Philippines’ drug problem. The campaign waged since his election has drawn widespread international criticism.