Former child star Sophie Nyweide has died at the age of 24.

The actress - who played the daughter of Michelle Williams and Gael Garcia Bernal's characters in 2009 romantic drama 'Mammoth' - passed away in Bennington, Vermont, on 14 April, and her mother, former actress Shelly Gibson, told The Hollywood Reporter that "police there are investigating".

While no details about her death have been given, in an obituary posted on Legacy.com, Sophie's family told how she "self-medicated" to cope with "trauma and shame".

They wrote: "Sophie was a kind and trusting girl. Often this left her open to being taken advantage of by others.

"She wrote and drew voraciously, and much of this art depicts the depth she had, and it also represents the pain she suffered. Many of her writings and artwork are roadmaps of her struggles and traumas. Even with those roadmaps, diagnoses and her own revelations, those closest to her, plus therapists, law enforcement officers and others who tried to help her, are heartbroken their efforts couldn't save her from her fate.

"She self-medicated to deal with all the trauma and shame she held inside, and it resulted in her death.

"She repeatedly said she would 'handle it' on her own and was compelled to reject the treatment that might possibly have saved her life."

Sophie had appeared in seven movies by the age of 10, with her credits including 'Bella' (2006), 'And Then Came Love' (2007), 'New York Serenade' (2007), 'Margot at the Wedding' (2007), 'Shadows + Lies' (2010), and 'Noah' (2014)'. She also appeared on a 2007 episode of 'Law and Order', and her last onscreen credit was an appearance on hidden-camera show 'What Would You Do?' in 2015.

Sophie's family asked for donations to anti-sexual violence charity RAINN to be donated "in lieu of gifts or flowers" in her memory.

A memorial service has yet to be arranged.