DAVAO CITY — Davao City Rep. Paolo Duterte is disappointed over the decision of the International Criminal Court to keep his father, former President Rodrigo Duterte, in custody at The Hague, Netherlands.

"This decision is a gross and disgraceful miscarriage of justice. It is not law — it is a political theater," Rep. Duterte said in a statement posted on his Facebook page Friday following the ICC’s rejection of the former President’s request for release on medical grounds.

Former President Duterte's eldest son stressed that his 80-year-old father, who is no longer in power, has been the subject of political persecution since leaving office.

“He is definitely not a flight risk. He is much loved in his own country and would have wanted nothing more but to stay there for as long as his Creator permits him,” Rep. Duterte said.

Rep. Duterte warned people behind his father’s detention. He said he will make sure kidnappers will pay for their crimes.

“To all kidnappers of my father, I will make sure that you will pay for this crime that you have committed. To the CIA (Central Intelligence Agency) who connived in this criminal act, my father’s kidnapping will not silence him,” the lawmaker said.

He added that the ICC’s ruling could further fuel public anger.

“You might just have helped in making him a martyr. The anger of his people over his baseless imprisonment might just worsen, just as their love for him will grow bigger."

“We will appeal. We’ll fight this by the book. And by the grace of the Almighty, my father will go home to his beloved Philippines,” Rep. Duterte said, as he thanked all Filipinos for their continued support.

The ICC found former President Duterte’s detention “necessary,” ruling that he posed a flight risk and could potentially influence witnesses if released.

The elder Duterte faces charges for alleged crimes against humanity in connection with the thousands of deaths during his administration’s war on illegal drugs.