Her sudden death shocked her "That '70s Show" fans, but now an investigation shows that Lisa Robin Kelly's death may hold some secrets.

According to TMZ, The LA County Coroner and the LA Country Sheriff are opening up an investigation to determine the actress' real cause of the death.

As a result, Lisa's manager Craig Wyckoff cleared up the rumors. Mr. Wyckoff spoke to FOX411 about why the LA County Coroner Office will conduct an investigation on Lisa's mysterious death, claiming it's a "non-routine" situation.

"It's not routine, but in the state of California, if a woman is found dead a certain age, then they have to do an investigation," he said.

Mr. Wyckoff also disagrees with the Coroner not being notified immediately, stating "She did die Wednesday night, but everyone was notified immediately."

As previous reported by GossipCenter, Lisa had reportedly died in her sleep last Wednesday (August 14) while staying at a California rehab facility. She was only 43.