The US man accused of kidnapping three women, holding them in his home for a decade and raping them has pleaded not guilty to all charges.
The murder charge involves his allegedly starving and punching a pregnant woman in captivity until she miscarried.
Castro, 52, is accused of snatching the three women and keeping them - sometimes restrained in chains - along with a six-year-old girl he fathered with one of them.
Prosecutors say the investigation will continue and they are leaving the door open to pursuing a death penalty case against Castro.
News that the women had been found alive electrified the Cleveland area, where two of the victims were household names after years of searches, publicity and vigils. But elation soon turned to shock as allegations about their treatment began to emerge.
The indictment against Castro alleges he repeatedly restrained the women, sometimes chaining them to a pole in a basement, to a bedroom heater or inside a van. It says one of the women tried to escape and he assaulted her with a vacuum cord around her neck.
All the while, Castro continued driving a school bus and playing bass in local bands, with fellow musicians saying they never suspected a thing. He was fired as a bus driver last autumn after leaving his bus unattended for several hours.
Castro was arrested on May 6, shortly after one of the women broke through a door and yelled to neighbours for help. She told police in an emergency call: "Help me. I'm Amanda Berry. I've been kidnapped, and I've been missing for 10 years, and I'm, I'm here, I'm free now."
The women - Ms Berry, Gina DeJesus and Michelle Knight - disappeared separately between 2002 and 2004, when they were 14, 16 and 20 years old. Each said they had accepted a ride from Castro, who remained friends with Ms DeJesus' family and even attended vigils over the years marking her disappearance.