Sia has tweeted her support of FKA Twigs by revealing that she was unknowingly in an "adulterous relationship" with Shia LaBeouf.
The 44-year-old Australian singer made the information public after the American actor starred in the 2015 music video for her song Elastic Heart.
Sia wrote: "I too have been hurt emotionally by Shia, a pathological liar, who conned me into an adulterous relationship claiming to be single. I believe he's very sick and have compassion for him AND his victims. Just know, if you love yourself- stay safe, stay away."
This comes after Twigs accused LaBeouf of sexual battery, assault, and infliction of emotional distress, citing a lawsuit, as per the New York Times.
The singer then tweeted her support of FKA Twigs, posting a link to a Variety article and writing: "Also I love you @FKAtwigs
"This is very courageous and I'm very proud of you.
"FKA Twigs Sues Ex-Boyfriend Shia LaBeouf for Sexual Battery - Variety".
Until now, it had never been made public that Sia and LaBeouf had dated or when the two were in a relationship.
At the time of LaBeouf's appearance in Sia's music video, she was married to documentary filmmaker Erik Anders Lang. The couple separated in December 2016 after marrying in 2014.
The incident at the heart of Twigs' lawsuit against LaBeouf occurred just after Valentine’s Day 2019 and cited an incident where the actor was driving recklessly with her in the car and threatening to crash if she did not profess her love for him.
According to the lawsuit, she begged the actor to pull over, and he eventually did at a gas station, following her out of the car and assaulting her.
"I'd like to be able to raise awareness on the tactics that abusers use to control you and take away your agency," Twigs told The New York Times.
Twigs and LaBeouf met on the set of Honey Boy in 2018, but the two did not begin dating until filming had finished, per news.com.au.
As well as this incident, Twigs claimed that LaBeouf knowingly gave her a sexually transmitted infection and would squeeze her hand until it bruised.

LaBeouf said in an email to The New York Times: "I'm not in any position to tell anyone how my behavior made them feel. I have no excuses for my alcoholism or aggression, only rationalizations.
"I have been abusive to myself and everyone around me for years. I have a history of hurting the people closest to me. I'm ashamed of that history and am sorry to those I hurt. There is nothing else I can really say."