Dolores's passing likely comes as a crushing blow for Steven Avery, who served 18 years in prison for a wrongful conviction before being arrested again in November 2005. Steven Avery spent the majority of his adult years in jail as a result of what some believe to be a series of oversights on behalf of the state. Here's what you should know about Dolores's cause of death.

"Update: Fate dealt another cruel blow to Steven Avery today right before his birthday tomorrow, his mother Dolores Avery passed away at 6.50 a.m.," Kathleen tweeted. "He needs your support now more than ever. R.I.P. Ma Avery."

"Sweet Dolores Avery always had a kind word for us. Loved her family, lived for the day Steven was freed, never stopped believing in him and his innocence," Kathleen wrote in a separate tweet. "Her spirit and devotion will sustain us. Steven knows she is watching over him."

"Losing my parents before I got out has always been my worst nightmare. Now it has happened," Avery told TMZ. "I worry my Dad will not live to see me as a free man. Today I lost the person I most wanted to take care of and give a better life when I am freed. I cannot put in words the pain of losing my mom."

It's understood that Dolores died of dementia. As her son Earl told TMZ, she spent her last weeks in hospice.