[13][dead link‍] These activities helped his progression to Serbian presidency membership, and in 1990 he was elected to the Assembly of Serbia as a member of parliament for the Grocka—a suburb of Belgrade—although he did not live there.

In July 1991, he made another historic statement in Nikšić: "Here we will build a great Serbian state, with the border on the left shore of Neretva and Dubrovnik as the capital".

[13] Kertes reached the ultimate and the most lucrative peak of his career when he was appointed the head of the Yugoslav Customs Office in 1993, a post he held until 6 October 2000.

[13] They were a financial source for a vast range of operations, including funding the paramilitary units in the Croatian and Bosnian wars, money laundering in foreign off-shore banks, and filling private pockets of people close to Milošević.

[13] From his position, Kertes distributed an enormous number of gifts, chiefly vehicles and luxury goods, and the beneficiaries ranged from underdeveloped villages, through various state and local officials, to various special police, military and paramilitary units.

[13] After the overthrow of Slobodan Milošević on 5 October 2000, activists of the Democratic Opposition of Serbia broke into the customs headquarters, where they found Kertes and his associates shredding documents.

Other items found in the suite included US$ 1.3 million in various currencies, 18 pounds of drugs, about 50 weapons, and ten bulletproof luxury cars.

[13] After two retrials, in February 2007, Kertes was sentenced to 2.5 years in prison for providing a truck to the executioners of opposition politicians in the 1999 Ibarska magistrala assassination.

Among other crimes, the prosecution charged the group, consisting of Milošević, Jovan Zebić, and Nikola Šainović with transferring 120 million German marks to Cyprus banks, where the trace was lost.

[16] In November 2012, the Appellate Court reached its final verdict of six years and six months in prison for Kertes for illegal transfer of money to Cyprus and embezzlement of state budget for 1.5 million dinars.