Are you taking about Harold "Pete" Guyette? Wasn't he sentenced to life without parole for the shootings, not death row? Didn't he get off because his confession was deemed unconstitutional?
Anyway, this does bring up an interesting legal point. A person can be falsely accused of murder but legally only for a murder that actually occured. A person can be falsely accused of rape but that rape need not ever have actually happened to obtain a conviction. This is a contributing factor to why murder is often treated as a capital offense but rape, even aggravated rape or child rape, is not. (Ironically, a murder conviction can be obtained on strictly circumstantial evidence, whereas rape is very difficult to prove without conclusive physical evidence.)
Legally then, murder is "worse" than rape. However, morally, if one looks at crime of all types as forms of theft, is not the theft of a life always equally heinous? In the case of murder the life is stolen abruptly and completely, but in cases of rape a life is stolen piecemeal over time depending on the severity of the offense. Perhaps certain rapes ought to be treated a capital crimes, worthy of permanently ridding society of the offender.