The 83-year-old was rushed to Bakersfield hospital three days ago for emergency medical treatment.
He has since remained with sources telling American entertainment news outlet TMZ that “it’s just a matter of time” before he passes with Manson said to look “ashen”.
Manson was found guilty of first-degree murder and conspiracy to commit murder after he ordered members of his cult, known as the Manson Family, to commit nine murders across July and August in 1969, including pregnant actress Sharon Tate.
While not present at the murders, Manson was denied release in 2012 when he appealed for parole. He is not eligible to apply again until 2027.
Yet a source said: “It’s not going to get any better for him” with regards to his health.
In January he refused an operation after being rushed to hospital with severe intestinal bleeding and a sigmoid lesion. Even though he changed his mind he was unable because he was too weak.