In the sentence "The results released yesterday showed..." the word "released" acts as the adjective. Specifically, the adjective formed from the past participle and -ed ending (verb + ed).
The meaning of this sentence is: The reaults that were released yesterday showed....
Other examples of such adjectives (looking like verbs) are: 'excited', 'interested', and 'bored'.
I hope it helps,
Originally Posted by HK