The former f (x) member was found dead at her home in Seongnam today, with police saying her death was a suspected suicide.
"So far, it seems she killed herself, but we will leave all possibilities open and investigate."The manager had gone to Sulli's home to check on her after not hearing from her for more than 20 hours, following a phone call the previous night at 6:30 p.m. local time.
Sulli was reportedly found dead at 3.20pm after her manager went over to her house when he couldn't contact her.
In a statement sent to reporters, SM Entertainment, Sulli's agency, said her death was "very hard to believe and sorrowful".
Cyberbullying has been a problem in South Korea's entertainment scene for decades. K-pop stars usually face pressure not to date because it can disillusion their fans. "We can not believe the situation and we are simply in a state of grief", reads the statement.
The former girl group member had made her return to music this year.
When she returned the following year, she left the group and turned to acting.
The star was a hugely popular K-pop singer with over six million Instagram followers.
She said then that she was mentally and physically exhausted after suffering from malicious comments and false rumours online. People hurt me, so everything fell apart.
Previously in one interview, Sulli opened up about her panic disorder and social phobia, saying in a teaser for her reality show Jinri Store past year: She had been experiencing social phobia and panic disorder.