I'm surprised the other robber isn't charged with murder. His accomplice died which means he's technically on the hook for his death as well.
The crime is called felony murder and I'm kind of surprised he wasn't charged as well. Here's the statute for felony murder in Oklahoma from what I can find.
"A person also commits the crime of murder in the first degree, regardless of malice, when that person or any other person takes the life of a human being during, or if the death of a human being results from, the commission or attempted commission of murder of another person, shooting or discharge of a firearm or crossbow with intent to kill, intentional discharge of a firearm or other deadly weapon into any dwelling or building as provided in Section 1289.17A of this title, forcible rape,
robbery with a dangerous weapon, kidnapping, escape from lawful custody, eluding an officer, first degree burglary, first degree arson, unlawful distributing or dispensing of controlled dangerous substances, or trafficking in illegal drugs." Okla. Stat. tit. 21, § 701.7 (2006).