Strikeforce heavyweight champion Alistair Overeem has tested negative for anabolic steroids and drugs of abuse based upon independent testing that was administered by the promotion, CEO Scott Coker told Sherdog.com on Friday.Six of the 10 tested main-card athletes from Saturday’s Strikeforce “Heavy Artillery" event in St. Louis have passed the in-house drug tests administered on the eve of the event, said Coker. They include Antonio Silva Joey Villasenor , Ronaldo “Jacare” Souza, Rafael “Feijao” Cavalcante and Antwain Britt.Test results for Overeem’s challenger Brett Rogers Roger Gracie , and Kevin Randleman are still pending, said Coker.An independent on-site technician from a local laboratory conducted the urinalysis screening in the event’s host hotel following the official weigh-ins last Friday. The Missouri Office of Athletics, which oversaw Saturday’s event, also conducted random post-fight testing, which led to the promotion’s decision to sweep the entire main card on its own.“When the commission here said they’d only be random testing, I didn’t want there to be an ounce of doubt and have all these critics say, ‘Ah, Alistair didn’t get tested, Feijao didn’t get tested,’” Coker told Sherdog.com last Saturday in an exclusive video interview Missouri commissioner Tim Leuckenoff told Sherdog.com prior to the event that the regulatory body would test for “all illegal and unprescribed drugs.” Lueckenoff said that the results would be kept confidential, per the state’s testing protocol, but that if the state agency filed a disciplinary case against an athlete for a positive drug test, the results would become public information when the case is filed with Missouri’s Administrative Hearing Commission.