The death of 32-year-old actress Misty Upham has shocked many.

Now Juliette Lewis, Upham's co-star from the film "August Osage County" is revealing that she believes police do a murder investigation into the cause of the Native American actress's death.

"Misty Upham survived many things that many don't early on in life," Lewis wrote on Instagram, alongside a cheerful picture of her and Upham. "She fought for the voiceless feircely. She understood suffering and the deepest pain. She had a presence everyone saw and felt. It is this presence that will continue. Out of the dark space in which her light got dimmed. I will remember her as tuff. Wise. Funny. Spiritual. And hopeful. This is another great reminder to call and check on someone when you think to. Not when its too late. RIPMistyUpham."

Upham's body was discovered by her uncle on Thursday, Oct. 16, in a ravine near the White River located in Auburn, Washington.

"At this point we do not have any evidence or information to believe there is foul play," said a spokesperson for the Auburn police department.

Initially, reports claimed that Misty's father Charles believed his daughter may be suicidal after going off of her medication for bipolar disorder.

However, Tracy Rector, a filmmaker who was a longtime friend of Upham's told The Hollywood Reporter that the family does not believe the actress took her own life.

"The family has stated that, after seeing the body, they still do not feel that Misty Upham committed suicide," stated Rector.

Rector also indicated that the Upham family does not believe the Auburn police department did enough to look for the actress after she was reported missing on Oct. 6.

"First and foremost," Rector told THR, "the family wants everyone to know that the Auburn police did not help with this situation at all. They refused to help. When she disappeared on Oct. 5, the family knew something was seriously wrong - it was out of character for her to be gone so long without being in touch - and they repeatedly went to the police, who insisted there was no cause for concern."

Upham lived on the Muckleshoot Reservation in Washington, which allegedly has longstanding bad blood with the local Auburn authorities.

Lewis, who worked with Upham on "August Osage County," took to Twitter to plea with the Auburn police department to do a thorough investigation into the late actress's death. Lewis even suggested that her deceased friend could have been murdered, considering she had accumulated enemies over the years while fighting for causes that she believed in.

I cant sleep. Too much darkness. I feel so sad about Misty. I know she has more to say. And about how she died. #RIPMistyUpham

— Juliette Lewis (@JulietteLewis) October 17, 2014

@JulietteLewis when I spoke to her last she was afraid, yet she wasn't backing down. She did not kill herself — Joe Gentile (@KrueJoe23) October 17, 2014

#RIPMistyUpham Misty spoke out alot against injustices within Native community. And had known enemies. Police must do an investigation.

All I want is a thorough investigation into MistyUpham's deathAnd Not old Native American tensions or her past emotional probs to prevent it

— Juliette Lewis (@JulietteLewis) October 17, 2014

Lewis also retweeted a post that Upham wrote on Sept. 28, just days before her disappearance, in which she indicates that she was followed by an individual who disagreed with the actress publicly voicing her opinion on an undisclosed subject.

Indian Trader just followed me. Please everybody, alter your speech. Censor yourself and walk on eggshells so not to hurt their feelings... — Misty Upham (@MistyUpham) September 29, 2014