Misty Upham has been missing since October 5.

The 'August: Osage County' actress, who suffers from a medical condition, was last seen by her family six days ago when she left her sister's apartment in Muckleshoot, Washington.

Her father Charles Upham released a letter via the Indian Country Today, saying: ''Misty is considered an endangered missing person due to a medical condition. She has not been in contact with her family or friends since her disappearance.''

Police arrived at Misty's apartment, which she shares with her parents, last Sunday after receiving a suicide call, but when they arrived she had already packed some of her belongings and left the property.

Commander Steve Stocker told PEOPLE.com: ''Our officers responded to her apartment where she lives with her parents on Sunday for a suicidal call. When our officers got there, she had already packed up some belongings and left the apartment, so the officers were not able to contact or find her.''

This isn't the first time police have been called to her apartment as within the last year they've reportedly responded to four suicidal calls from Misty's home.

However, the brunette beauty's dad doesn't believe she would actually take her own life, but admits she recently changed her medication.

He told the Hollywood Reporter: ''She had recently changed her medication, so she was sort of having erratic behaviour. She told me and her mum that we didn't have to worry about her anymore ... I thought it sounded suicidal myself, so I called the police. She's always been a suicidal person.''

''She used to make [suicide] threats sometimes, but she never went through with it. I think that she is either in a place where she can't get help - maybe she fell down and broke her leg and something, or she got in with the wrong crowd. I don't think she would have taken her own life. I don't want to think she is dead.''