Valerie Wolski, who was 41, was alone and providing care to a man with limited mental capacity in February 2011 when she was strangled.
Alberta Justice spokeswoman Michelle Davio says the Crown considered the evidence and there is not enough to recommend charges.
The statute of limitations for laying charges in Wolski's death expires Monday.
Terrence Wade Saddleback was charged with manslaughter, but found mentally unfit to stand trial.
Davio says a fatality inquiry, which would examine all circumstances of Wolski's death but not lay blame, is pending.
Saddleback is currently at Alberta Hospital and is subject to regular mental health assessments.
A risk assessment done on Saddleback after he attacked a female staff member in Wetaskiwin, Alta., in July 2009 warned of the consequences for anyone caring for him.
It took five RCMP officers and a male staff member to subdue him using handcuffs and pepper spray.
Graham Jones, Saddleback's legal guardian, has said he warned the Canadian Mental Health Association that they needed to be careful with him, but his concerns were shrugged off.
A preliminary report by Occupational Health and Safety said the province's Persons With Developmental Disabilities Board failed to warn Wolski or her employer that Saddleback was violent and dangerous.
The response by Persons with Disabilities, along with information on its appeal of an order to conduct more due diligence with subcontractors, has not been released to the public.