Aaron Hernandez Lawyer Jose Baez Says 'Suicide' Could Actually Be Murder

Aaron Hernandez may not have died as the result of suicide ... it could be murder orchestrated within the prison walls -- so claims the lawyer who represented him.

We've learned attorney Jose Baez -- who just got a not guilty verdict for Aaron last week in the double murder case -- has launched an investigation on behalf of Hernandez' family and they are not buying the suicide story.

We're told Baez believes this could be a murder either by inmates or the folks who run the prison.

Baez says the family is "devastated" and does not believe Aaron was in a frame of mind to take his life.

Baez told TMZ Sports just last week Aaron was in a good place and optimistic the separate murder conviction would be overturned.