It has been revealed that Oklahoma beheading suspect Alton Alexander Nolen (a.k.a. Jah'Keem Yisrael) had been serving time in state prison serving a six year concurrent sentence for cocaine and marijuana possession as well as assault of a state trooper. Nolen went to prison in March 2011, but was released in March 2013.
Oklahoma has a law which states that inmates must serve a minimum of 85% of their sentence if it is for a violent offense. However, under Oklahoma law, the drug offenses are considered non-violent.
Anyway you look at it, had Nolen not been released from prison early then Colleen Hufford would still be alive.
On the other hand, it appears that Nolen converted to Islam while in prison and may have been radicalized there. In which case, it is entirely possible that Nolen could have been even more dangerous had he served his full sentence.