MANILA, Philippines -- A retired Philippine police officer said Monday that President Rodrigo Duterte, when he was a mayor, ordered and paid him and other members of a so-called liquidation squad to kill criminals and opponents, including a kidnapping suspect, his family and a critical radio commentator.

Human rights lawyers who presented Arthur Lascanas at a news conference said the allegations could be grounds for impeaching Duterte, adding that his alleged role in the killings may not be covered by his presidential immunity.

Sen. Antonio Trillanes IV, who helped the lawyers from the private Free Legal Assistance Group present Lascanas in a news conference at the Senate, said he would ask his colleagues to immediately investigate the explosive allegations.

Phillippines ex-cop Arthur Lascanas details alleged extrajudicial killings for Rodrigo Duterte "Davao Death Squad" - CBS News