The former Two and a Half Men star's second wife, Denise Richards, has been looking after Sheen's four-year-old sons Bob and Max since Mueller was stripped of custody and admitted to a drug rehabilitation facility in May (13).
She spent Friday night (01Nov13) with her kids for the first time in months, and has since revealed plans to regain full custody - but the news angered Sheen and he launched into a Twitter.com rant that morning to slam officials at America's Department of Child and Family Services (Dcfs) for their handling of the case.
He unleashed another tirade against Mueller during an interview on U.S. gossip show Tmz Live last week (ends01Nov13), when he warned there will be a "reckoning" after accusing the recovering addict of putting their boys' lives in danger by allegedly using illegal substances while they were in her care.
He added, "I will exercise every resource at my disposal. I will, I will, I will, I will empty my entire war chest and if I can't get it done, I know a guy who can."
His fiery comments reportedly prompted authorities to ban him from visiting his boys back at Richards' house on Saturday (02Nov13), and prompted Mueller to file court papers for an immediate protective order.
Her motion was rejected by a Los Angeles judge on Monday (04Nov13), although she has been given another opportunity to argue her case at a hearing next month (Dec13), reports Tmz.com.
Sheen and Mueller have been fighting over their boys since splitting in 2010 after two years of marriage. Their divorce was finalised in 2011.