AceShowbiz - Naomi Judd's cause of death has been revealed. Multiple sources told PEOPLE that the one-half of The Judds died at the age of 76 by suicide after years of struggling with mental illness.

Naomi's family has yet to confirm the report. However, her daughters Ashley Judd and Wynonna Judd previously declared that they "lost our beautiful mother to the disease of mental illness."

"We are shattered. We are navigating profound grief and know that as we loved her, she was loved by her public," the sisters further noted in their announcement. "We are in unknown territory."

Naomi was a lontime advocate for mental wellness. In an open later for Mental Health Awareness Week in 2018, she wrote, "For everyone mourning the death of someone who committed suicide, an inevitable question arises: Why did this happen? Unfortunately, we don't have very good answers.

"We do know that suicidal behavior accompanies many behavioral brain disorders such as schizophrenia, bipolar disorder, and depression," the country legend added. "Suicide is actually one of the leading causes of preventable death among these mental illnesses."

"To understand this issue better, we have to bring the study of suicide into mainstream neuroscience and treat the condition like every other brain disorder," she added. "People who commit suicide are experiencing problems with mood, impulse control and aggression, all of which involve discrete circuits in the brain that regulate these aspects of human experience, but we still don't understand how these circuits go haywire in the brains of suicide victims."

Just one day following her passing, Naomi was inducted into the Country Music Hall of Fame. Her daughters Ashley and Wynonna attended a ceremony in Nashville, Tennessee on Sunday, May 1 to accept the honor.

"My momma loved you so much, and she appreciated your love for her and I'm sorry that she couldn't hang on until today," Ashley tearfully told the audience. "Your esteem for her and regard for her really penetrated her heart, and it was your affection for her that did keep her going in these last few years."