Mueller, 32, checked into The Canyon rehab facility in Malibu last Tuesday, according to TMZ.com.
Mueller's lawyer, Yale Galanter, told PEOPLE he was not prepared to comment on the report. But one source confirmed to PEOPLE, "Brooke is in rehab."
Also, Mueller was allegedly seen partying while out with Sheen, 44, just hours before checking into rehab, reports RadarOnline.com.
The latest reports follow a whirlwind of events which began on Christmas Day, when Mueller and Sheen, 44, got into a fight in Aspen, Colo. Sheen was arrested and charged with domestic violence.
Mueller was then hospitalized for what was described as a severe wisdom tooth infection that led to pneumonia. After that, she checked into a North Carolina "wellness program" – for "rest" rather than addiction rehab, according to her lawyer.
Before Mueller entered this latest program, a source told PEOPLE: "Brooke is going to go into rehab as soon as possible. It is the best thing for her to do. She really liked the programs in North Carolina and would like to go back there at some point."