Mark Salling kept to himself during the time leading up to his death.
The 35-year-old actor died of apparent suicide on Tuesday, and a source tells ET that he recently "distanced himself very much from the friends he was closest to."
ET's source says that before Salling was arrested for possession of child pornography on Dec. 29, 2015, "he would often have friends over to his home in Sunland, [California]." "He was himself the most when he was at home. In fact, he had a bird sanctuary in his backyard where he rescued birds then rehabilitated them," the source recalls. "He was very proud of that."
According to our source, Salling's friends weren't aware of the severity of his demons, but believed he was "troubled and tormented." "He had a very mysterious side. I felt like I didn't completely know who he was," the source explains. "He enjoyed visiting family in Texas and saw his trips back home as an escape from L.A. and the Hollywood scene."
A spokesperson for the Los Angeles County Coroner's office told ET that Salling was pronounced dead at the scene at around 9 a.m. on Tuesday. His death is being investigated as a suicide by hanging.
See more in the video below.
Mark Salling Dead at 35: A Timeline of the 'Glee' Star's Struggles and Legal Issues
Mark Salling's Death Being Investigated as Suicide by Hanging
Mark Salling's Former 'Glee' Cast and Crew React to His Death