Prosecutors will decide whether to refile charges against Ramos. He was accused of killing 31-year-old Michael Galindo during a violent outbreak at the Tecumseh State Correctional Institution.
The bodies of Galindo and 39-year-old Damon Fitzgerald were found after authorities restored order.
Authorities have said the uprising began because inmates were angry that prison staffers had confiscated 150 pounds (68 kilograms) of homemade alcohol from them.