There's no evidence that an SU-25 was close to MH17. And, in any case, an SU-25 is not capable of shooting down an airliner flying at 33,000 feet. It was designed to provide close air support to Soviet ground forces. Its service ceiling is 23,000 feet.
Not true...within three days the Russian Defense Ministry released radar imagery that they said indicated a Ukraine military aircraft was in proximity to the Malaysian airliner before it went down. To date this information has not been refuted, and the Ukrainians in particular have not released any information other than denials.
And, in any case, an SU-25 is not capable of shooting down an airliner flying at 33,000 feet.
Wrong again. While an SU-25 cannot sustain such an altitude for long periods, it certainly has the ability to ascend to 33,000ft for a short while...long enough to fire a missile... if it chose to. I don't think this is what happened, but it is certainly within the capability of the SU-25 to do so.