RadarOnline.com has obtained shocking new details about fallen OC star Mischa Barton doing drugs leading up to her spectacular public fall from grace -- highlighted by her being taken to Cedars-Sinai Medical Center in Los Angeles last week where she was put on involuntary psychiatric hold.
Our new information reveals an ‘out of control’ Barton rolling some marijuana joints inside her hotel room at The St Martins Lane Hotel at last year’s London Fashion week.
"Mischa was obviously out of control, she was behaving like an addict and I’m not surprised by the latest turn of events," an insider -- who spent the night partying with the fallen starlet -- exclusively revealed to RadarOnline.com.
Barton had gone to London to attend various fashion shows and get away from Los Angeles where her partying had already spiraled out of control following her DUI and marijuana arrest in December 2007.
But when she arrived in the British capital nothing changed, and she continued to abuse both alcohol and drugs during one crazy night.
The insider told RadarOnline.com: "I first met up with Mischa at an after party at Portland Place and she seemed like a really fun girl who was keen to make new friends.
"She was a little anxious because the venue was so crowded, so, she invited me and a couple of friends to the Bungalow 8 club below St Martins Lane Hotel where she was staying.
"When we arrived at the club she started drink tequila and she was getting a little edgy because some paparazzi had followed her.”
According to our source, Barton then disappeared into the bathroom for a ‘very long time’ and when she emerged she had lost her Blackberry phone.
The actress was distraught because it contained a lot of personal information and she asked several people to help find it for her.
But when it didn’t show up she got very agitated before asking to go to another club so she could continue to party.
“When we were in the taxi she told us that she loses about ‘six phones a year’ before we went onto The Groucho Club.
“Mischa bought us all some cappuccino cocktails and then we went-on to Sugar Hut which is a gay club in London.
“We were all having a good time but Mischa was getting pestered by a guy in a wedding dress and she wanted to leave and return to her hotel.
“She discussed getting some marijuana with somebody in our party, and she gave him some cash so that he could buy it from a dealer he knew.”
The party-goers then returned to Bungalow 8 where supermodel Kate Moss was sitting with a group of friends and after having a few more drinks they agreed to go to Barton’s room on the 4th floor of the hotel.
Our source told us: “When we got inside the room Mischa instantly offered us some drinks from her mini-bar before getting out her laptop and laughing at a video of Kimberley Stewart falling off a motor bike on YouTube. She told us that she hated Kimberley and Paris Hilton because they had made fun of her after her DUI arrest but that Naomi Campbell had phoned her to offer some support. After some time she went into her purse and took out a bag of marijuana - when she put her purse down I could see traces of white powder inside it.
"She then started grinding-up the marijuana on the hotel table before rolling two joints and lighting one and smoking it. We sat with her for at least an hour watching some television before we left her to fall asleep around 3 a.m. because she had a FHM magazine photo-shoot the next day. Mischa was a sweet person but she is really foolish as both her drug and alcohol consumption was very open. She didn’t seem to be able to control herself and I’m not surprised that it has snow-balled and that she is now in hospital. In my opinion she is going to need a lot of help to fully recover from what I saw that night in London."
Production on Barton’s new show The Beautiful Life, in which she portrays a supermodel, has been temporarily postponed. A rep for the CW claims it’s because the show’s sets are not finished.