Nalyvaichenko said Zakharchenko gave the order to fire Grad multiple rocket systems on the Ukrainian checkpoint and the passenger bus near Volnovakha.
"The direct order to use Grads was given deliberately by the leader of the so-called DPR to scare the civilian population," Nalyvaichenko said.
"The investigators have records of these telephone conversations," he said.
"The leaders of the so-called DPR knew that the passenger buses usually went with civilians on the route from Slaviansk to Mariupol, that’s why they deliberately used a powerful weapon," he said.
"Zakharchenko has been already made a suspect. He will be detained by Ukrainian or international justice," Nalyvaichenko said.
In addition, General Prosecutor of Ukraine Vitaliy Yarema, who was also present at the briefing, said that the Ukrainian side has already submitted to Interpol the details of all the leaders of the so-called DPR and LPR, including Zakharchenko, for the international wanted list.
"Interpol hasn’t declared him wanted yet, but I hope it will announce this soon. Zakharchenko is a person who will be pursued all over the world until his last days," Yarema said.
As UNIAN reported earlier, on January 13, twelve people were killed, and another 17 wounded, including one soldier, in east Ukraine when a passenger bus was hit by the blast from a rocket fired by Russian-backed militants.