Don't understand the ending (SPOLIER)

For one, because they weren't going to have it pinned on Marco when he wasn't at fault for the assassination, and also I think to get some kind of word out about the Manchurian Global company and let the public know it's dirty dealings with anybody from the place, they had connected it with a second person from the place as well.

I thought this was extremely obvious. After the cover up you see the people in the company very concerned because they are in the media now and possibly being investigated. Their plans have failed and evidence is piling up

because they where a part of the murder, just like with kennedy. they saw marco coming in and didn't do any thing.