On the third day of a hearing to decide whether Duterte should face trial on crimes against humanity charges over his "war on drugs", lawyer Nicholas Kaufman said the prosecution had failed to show his client had directly ordered any murders.

"There is no smoking gun in this case," Kaufman told the three-judge panel at the ICC.

"Not one witness relevant to any of the 49 incidents with which Mr. Rodrigo Duterte is charged will testify that he received a direct order from the former president to go out and kill someone," added the lawyer.

Duterte has not attended proceedings, waiving his right to appear. Kaufman says the 80-year-old is not mentally fit to follow the hearing.

The lack of evidence of a "causal nexus" between Duterte's words and alleged crimes "should be sufficient to convince any reasonable bystander... that Rodrigo Duterte is innocent of these charges levelled at him," said Kaufman.

Earlier in the week, the prosecution laid out their case: that Duterte played a "pivotal" role in a campaign of extrajudicial killings that saw thousands murdered.

Duterte personally drew up death lists, incited murders and then boasted about them afterwards, prosecutors alleged.

They showed multiple videos of the former president threatening to murder alleged drug users and joking about his skills in extrajudicial killing.

But Kaufman said the prosecution had "cherry picked" speeches, ignoring what he said were dozens of examples of Duterte stressing the need to act within the law.

"Do not kill if you are not in danger of losing your life," Kaufman cited Duterte as saying in one speech.

Following the week-long "confirmation of charges" hearing, the three-judge panel has 60 days to decide whether to proceed to a full trial.

A lawyer representing the victims told the ICC on Tuesday that the court was the "last refuge" for loved-ones in their search for justice.

Kaufman stressed: "The defence does not disrespect the soul of any deceased person, nor does it make light of the loss of life."