KIEV, Ukraine (AP) — Friends and colleagues of renowned journalist Pavel Sheremet, who was killed in the Ukrainian capital Kiev a year ago, marched Thursday morning across town to demand answers from authorities about why his brutal murder has not been solved.

Belarus-born Sheremet, whose investigations rattled authorities in Russia, Ukraine and Belarus, was killed by a car bomb in the center of Kiev on July 20, 2016. There has been no visible progress in the probe despite the Ukrainian president's promises of all-out efforts to solve the case.

Sheremet's friends, colleagues and activists gathered early Thursday morning around the time Sheremet was killed. About 200 people laid flowers and left candles at the intersection where his car blew up before setting off to march to the presidential administration to express their frustration with the investigation. Some of the mourners spray-painted "Who killed Pavel?" on the sidewalk outside the presidential administration and plastered a posted with Sheremet's portrait at the entrance to the National Police headquarters.

Ukrainian authorities have blamed Russia for contracting the killing but stopped short of giving detail.

"The results of the investigation are disappointing, and no new theories are named, investigators do not publicize any new facts," Sevgil Musayeva Borovyk, editor-in-chief of Ukrainska Pravda where Sheremet worked, said in comments carried by the Tass news agency. The journalist community "does not want law enforcement officials to cover their inaction and complete lack of professionalism."