By Jen Heger - Breaking Celebrity News Legal Editor

As pictures emerged of a disheveled Brooke Mueller appearing to be holding a tin foil crack pipe, and reports of an apparent drug relapse surface, she still retains custody of her twin boys from Charlie Sheen.

In addition, Breaking Celebrity News has exclusively learned why child protective services haven't visited Mueller or opened an investigation into her sons' welfare.

"The reason that DCFS haven't visited Brooke Mueller's home, to check on the boys, is because the department hasn't been called to do so, as simple as that," a source with knowledge of the situation tells Breaking Celebrity News. "DCFS can't just show up at someone's house and demand to interview the parents and children. DCFS goes out when a call has been made to alert the department about a concern involving a child, and that hasn't been in this situation."