Brooke Mueller's drug abuse history will be given to child protective services.

The third former wife of Charlie Sheen is embroiled in an on-going investigation to decide whether she can retain custody of the pair's twin sons, and her "medical records" could be made available.

"All of Brooke's medical records from the past four years since the twins were born, as well as all the rehabs she has been to, will be turned over to child protective services," an insider said. Temporary custody of Bob and Max, four, has been granted to Denise Richards, Charlie's second ex-wife.

Brooke, 35, is currently being treated in the Betty Ford Clinic for her 20th stay in rehab and her drug addiction will be thoroughly investigated ahead of the June 4 hearing which will determine who will have care of the twins for the next six months.

Child protective services could also ask the Drug Enforcement Agency for records of any prescription drugs she has taken and - while Brooke can refuse - social workers could get a subpoena to get information from her medical records.

It was previously reported Bob and Max would be allowed to visit their mother - in the company of a court-appointed monitor - in rehab yesterday for a few hours.