Ukraine's National Police sent 14 requests for international legal assistance in the investigation into the killing of journalist Pavel Sheremet, Serhiy Kniazev, the head of the National Police, told the Internet publication Ukrayinska Pravda.

"We used an opportunity to interact with other countries as part of international legal assistance and we sent 14 requests for international legal assistance. We have already received responses from some," Kniazev said.

The head of the National Police said he hopes the ratified agreement with Europol will help resolve the crime.

"Every link is being investigated in this case, every track and every little piece of evidence. We constantly go back to the large amount of information we have processed, including the videos, verifying and comparing information received in the next stages," he said.

"The theories of attempted murder in which the wrong object was chosen and conflict situations in personal life are not regarded as a priority," Kniazev said.

The head of the National Police said he believes the criminals knew very well what they were doing, professionally prepared for the crime, realized who they were planning to blow up and did not care if anyone else would be hurt in that.

"We are doing everything possible to resolve this crime, but more transparent proceedings, unfortunately, may harm the investigation and the people who are related to this case in one way or another," Kniazev said.

A car belonging to Olena Prytula, the head of the Ukrayinska Pravda online publication, was blown up while Sheremet was in it in central Kyiv at 7:45 a.m. on July 20, 2016. The journalist died on the spot soon after the explosion. Investigators said they believed the killing was connected to his journalistic activities in Ukraine and other countries.