Why did the authorities think the Winter Soldier is responsible for this attack?

Question

In the movie,

The attack that killed the Black Panther's father was attributed to the Winter Soldier based on a very low quality CCTV footage that caught the culprit's face.

How did they arrive at the conclusion that the Winter Soldier is responsible based on that purported evidence? It's not like he had recently been in the media spotlight (which would have led to a "Winter Soldier strikes again!" type of media response) so it felt a bit random to me that the Winter Soldier of all possible villains had come to mind, unless reliable analysis was made to arrive at this conclusion. Considering the quality of the purported evidence, how did they even arrive at this conclusion to an acceptable extent?

Answer 1

Alright, so, I've watched the movie yesterday, and

Zemo used an advanced mask to impersonate Bucky - after the fight in the airfield, Tony Stark gets a report from Friday, which explicitcly states that the real UN doctor's body was found, along with a mask made to look like "one James Buchanan Barnes" (direct quote from the movie, Berlin police report).

And with that item with him, he let himself be caught on a CCTV with most of his

fake

face uncovered, and an image of that quickly went public. This is why they thought Bucky did the bombing.

Answer 2

It was Zemo that framed Bucky, so that he can lure him out of his hiding place that no one was able to find. Since that CCTV footage was released to the public, all the news started posting Bucky's picture.

It would be easier to spot him this way, when most people around the world would have seen his face and would recognize him, like that newspaper seller that saw him.

MCU WIki states this as well; that Zemo used him as a scapegoat for the bombing that took place in Vienna which killed king T'Chaka.