mh17 buk fragment
Dutch RTL Nieuws journalist Jeroen Akkermans published a breaking story in March 2015 on MH17. He reported that he found parts of a BUK missile and warhead fragments at the crash site. He found these parts at November 10 or November 11, 2014 and had them analyzed by independent experts.

One interesting part found by Akkermans was a bow-tie shaped piece of rusted material. It looks like to be shrapnel part of the BUK warhead. One of the experts who looked at this fragment was Nicolas De Larrinaga of Janes. His quote published by RTL is "From the hour-glass form we can gather all the characteristics of an impact of a 9N314 warhead fragment. This fits perfectly."

However, judging by the exact position where the bow-tie was found by Akkermans, the fact the bow-tie was loose on the floor and the fact that the wreckage piece was turned over by people since the crash, it is likely this bow-tie was planted by someone.

buk fragment mh17
The fragment as it was found, in a pool of water that had collected in wreckage from the rear fuselage. This wreckage had previously been turned over, implying the fragment had not been there prior. There is no fragment damage on this portion of the wreckage, and the fragment couldn't have had enough energy to penetrate the cockpit and travel this far back into the plane.
[...] It seems very likely the bow-tie was planted just before Akkermans discovered it. It is very unlikely the bow-tie has been in the wreckage ever since July 17. Akkermans found the bow-tie very easily without having to do all kind of weird movements during his searching. [...] By planting a bow-tie, Russia was included as a state which could have shot down MH17. So in that case Ukraine could have planted the bow-tie. [...]

To read the full article, go here: BUK bow-tie found by Dutch journalist likely planted