According to the D.A.'s office ... when Dick was popped by cops, he was carrying a single Adderall pill -- and he didn't have a prescription -- so he could have been charged with possession.
But we're told ... the D.A.'s office decided against filing the drug charge because Dick had such a minimal amount. They also declined to file grand theft charges because Dick had already given the necklace back ... and there was no evidence he ever planned to keep it.