MANILA -- British-Israeli lawyer Nicholas Kaufman on Wednesday visited detained former President Rodrigo Duterte at the International Criminal Court detention center to discuss their case.

In an an ambush interview with ABS-CBN News' Zen Hernandez, Kaufman said he will be meeting his client to build up their defense. 

"I'm going to inspect the nature of the case against him. He's going to have to fight it and win it," said the lawyers, who was officially appointed as the former president's lead counsel last Monday.

READ: Nicholas Kaufman officially appointed as Duterte's legal counsel

When asked about the composition of their legal team, he said they are still in the process of putting it together.

Duterte, who was arrested last March 11 in Manila, filed a signed letter on March 14 nominating Kaufman as his "lead defense counsel."

According to documents made public on Wednesday, the ICC registry met with Duterte on Monday, March 17, where he confirmed his appointment of Kaufman as his counsel. Kaufman accepted his mandate on the same day.

Kaufman has 34 years of experience in international law, and previously represented former Congo Vice President Jean Pierre Bemba and former Central African Republic (CAR) minister Maxime Mokom, who were also charged with crimes against humanity before the ICC.

Duterte is facing charges of murder as a crime against humanity in the ICC over his bloody war on drugs during his administration.